RikoteMaster/aqua-rat-mcqa huggingface dataset:
Question: In a class of 20 students, 2 students did not borrow any books from the library, 8 students each borrowed 1 book, 5 students each borrowed 2 books, and the rest of the students each borrowed at least 3 books. If the average (arithmetic mean) number of books borrowed per student was 2, what is the maximum number of books that any single student could have borrowed ?
A.3
B.5
C.10
D.13
Answer: C.10
Explanation: The average number of books per student was 2means that total of 2*20=40 books were borrowed;
2+8+5=15 students borrowed total of 2*0+8*1+5*2=18 books;
So 40-18=22 books are left to distribute among 20-15=5 students, these 5 arethe rest who borrowed at least 3 books;
Tomaximizethe number of books one student from above 5 could have borrowed we shouldminimizethe number of books other 4 students from 5 could have borrowed. Minimum these 4 students could have borrowed is 3 books per student, so total number of books they could have borrowed is 4*3=12 books. So the 5th student could have borrowed is 22-12=10 books.
Answer: C.
Question: A certain basketball team that has played 2/3 of its games has a record of 18 wins and 2 losses. What is the greatest number of the remaining games that the team can lose and still win at least 3/4 of all of its games?
A. 7
B. 6
C. 5
D. 4
Answer: C. 5
Explanation: 18 wins, 2 losses - total 20 games played.
The team has played 2/3rd of all games so total number of games = 30
3/4th of 30 is 22.5 so the team must win 23 games and can afford to lose at most 7 total games. It has already lost 2 games so it can lose another 5 at most.
Answer (C)
Question: A cube is painted red on all faces. It is then cut into 27 equal smaller cubes. How many L cubes are painted on only 2 faces?
A.12
B.8
C.6
D.10
Answer: A.12
Explanation: 1) Draw a simple cube
2) Draw 9 squares on each face of the cube (so that it looks like a Rubik's Cube) - this is what the cube will look like when it's cut into 27 equal smaller cubes.
3) Remember that the OUTSIDE of the cube is the part that's painted....
The mini-cubes with 2 painted sides are ALL on the edge of the cube, in themiddleof the edge. There are 4 in front, 4 in back and 4 more on thestripthat runs around the left/top/right/bottom of the cube.L= 4 + 4 + 4 = 12. Answer A
Question: A computer program assigns consecutive numbers to the days of the week. Sunday is 1, Monday is 2, ..... and Saturday is 7. Every day, the computer program calculates the value of parameter D according to the following definition: D is the number of the day times the value of D on the previous day. If the computer calculated D to be 8 on Wednesday, what would be the value of D calculated on the following Saturday?
A.1680
B.1830
C.2250
D.2400
Answer: A.1680
Explanation: On Saturday, the value would be 7*6*5*8 = 1680
The answer is A.
Question: If the average marks of three batches of 55, 60 and 45 students respectively is 30, 55, 60, then the average marks of all the students is:
A.53.33
B.54.68
C.55
D.47.81
Answer: D.47.81
Explanation: Explanation:
Required average = (55 × 30 + 60 × 55 + 45 × 60/55 + 60 + 45)
= (1650 + 3300 + 2700/160)
= 7650/160
= 47.81
Answer: D
Question: Machine A takes 100 hours to complete a certain job and starts that job at 7AM. After two hour of working alone, machine A is joined by machine B and together they complete the job at 6PM. How long would it have taken machine B to complete the jobif it had worked alone for the entire job?
A.10.11
B.9.99
C.11.1
D.44.11
Answer: A.10.11
Explanation: Let us assume total job = 100 units
A finishes 100 units in 100 hrs(given)
Hence A (working rate)= 1 units /hr
Now Given that A works for 2 hr( so 2 units done) then A and B finish total work in 15 hours. Hence A and B finish 98 units in 9 hours. Of these 1x9=9 units were done by A. Hence B did 89units in 9 hours.
Hence B(working rate)= 89/9 units /hr
Hence B takes 100x9/89 = 10.11 hours to complete the job.
Answer A.
Question: An amount of Rs. 3000 becomes Rs. 3600 in four years at simple interest. If the rate of interest was 1% more, then what was be the total amount?
A.Rs.3776
B.Rs.3729
C.Rs.3720
D.Rs.3778
Answer: C.Rs.3720
Explanation: A = P(1 + TR/100)
=> 3600 = 3000[1 + (4 * R)/100] => R = 5%
Now R = 6%
=> A = 3000[1 + (4 * 6)/100]
= Rs.3720.
Answer: C
Question: Find the area of circle whose radius is 7m?
A.187
B.154
C.177
D.288
Answer: B.154
Explanation: 22/7 * 7 * 7
= 154
Answer:B
Question: A certain board game has a row of squares numbered 1 to 100. If a game piece is placed on a random square and then moved 5 consecutive spaces in a random direction, what is the probability the piece ends no more than 5 spaces from the square numbered 49?
A.15%
B.8%
C.11%
D.12%
Answer: C.11%
Explanation: No more than 5 spaces from 49 means in the rangefrom 49-5=44 to 49+5=54, inclusive. Total numbers in this range 54-44+1=11, the probability favorable/total=11/100
Answer: C
Question: The average marks of 30 students are 45 but after checking there are two mistakes found. After adjustment if a student got 45 more markes and other student got 15 less marks, then What will be the adjusted average?
A.45
B.44
C.47
D.46
Answer: B.44
Explanation: Answer
Total number of all students of the class = 30 x 45 = 1350
∴ New average after adjustment = (1350 - 45 + 15)/30 = 1320/30 = 44
Correct Option: B
Question: Suppose there are 4 books on fairy tales, 5 novels and 3 plays. They have to be arranged so that the books on fairy tales are together, novels are together and plays are together, but we no longer require that they should be in a specific order. In how many ways can this be done?
A.103680
B.113689
C.125569
D.136690
Answer: A.103680
Explanation: Explanation :
First, we consider the books on fairy tales, novels and plays as single objects.
These three objects can be arranged in 3!=6 ways.
Let us fix one of these 6 arrangements.
This may give us a specific order, say, novels -> fairy tales -> plays.
Given this order, the books on the same subject can be arranged as follows.
The 4 books on fairy tales can be arranged among themselves in 4!=24 ways.
The 5 novels can be arranged in 5!=120 ways.
The 3 plays can be arranged in 3!=6 ways.
For a given order, the books can be arranged in 24*120*6=17280 ways.
Therefore, for all the 6 possible orders the books can be arranged in 6*17280= 103680 ways.
Answer : A
Question: If five machines working at the same rate can do 3/4 of a job in 30 minutes, how many minutes would it take two machines working at the same rate to do 3/5 of the job?
A.45
B.60
C.75
D.80
Answer: B.60
Explanation: using the std formula
m1d1h1/w1=m2d2h2/w2
substituting the values we have
5*1/2*4/3=2*5/3*x (converted 30 min into hours =1/2)
10/3=10/3*x
x=1 hour
so 60 minutes
ANSWER:B
Question: In two alloys, copper and tin are related in the ratios of 4:1 and 1:3. 10kg of Ist alloy, 16 kg of 2nd alloy and some pure copper melted together. An alloy obtained in which the ratio of copper and tin was 3:2. Find the weight of the new alloy.
A.34kg
B.35kg
C.36kg
D.30kg
Answer: B.35kg
Explanation: suppose x kg of pure copper is melted with 10kg of Ist alloy and 16 kg of 2nd alloy , then
Pure cooper in new alloy = 10*4/5 + 16*1/4 +x = 12+x kg
Pure tin in new alloy = 10*1/5+ 16*3/4 = 14 kg
As per given condition
(12+x)/14 = 3/2
24+2x= 42
x=9 kg
Total weight of new alloy = 10+16+9=35 kg
ANSWER:B
Question: The least common multiple of positive integer f and 3-digit integer n is 690. If n is not divisible by 3 and f is not divisible by 2, what is the value of n?
A.115
B.230
C.460
D.575
Answer: B.230
Explanation: The LCM of n and f is 690 = 2*3*5*23.
f is not divisible by 2, thus 2 goes to n
n is not divisible by 3, thus 3 goes to f.
From above:
n must be divisible by 2 and not divisible by 3: n = 2*... In order n to be a 3-digit number it must take all other primes too: n = 2*5*23 = 230.
Answer: B.
Question: x/2y = 2a,then 2x/x-2ay=?
A.4
B.8
C.16
D.2
Answer: A.4
Explanation: x/2y=2a,
Then x = 4ay,
Now, 2x/x-2ay = (2*4ay)/(4ay-2ay) = 8ay/2ay = 4
ANSWER:A
Question: In how many different ways can 5 identical blue pants and 5 identical red pants be shared among 10 children such that each child receives a pant?
A.628800
B.4628800
C.2628800
D.3628800
Answer: D.3628800
Explanation: GGG RRR
Therefore total number of ways is
6! but there are two groups of 3 identical things.
Therefore total number of "different" ways is
10!/ (5!) (5!) = 3628800 ANS:D
Question: The sale price of an article including the sales tax is Rs. 616. The rate of sales tax is 10%. If the shopkeeper has made a profit of 12%, then the cost price of the article is
A.Rs. 500
B.Rs. 515
C.Rs. 550
D.Rs. 600
Answer: A.Rs. 500
Explanation: Solution
110% of S.P. = 616	‹=› S.P.=(616x100/110).
‹=› Rs. 560.
C.P.	‹=› Rs.(100/112 x 560)
‹=› Rs. 500.
Answer A
Question: k = 2^n + 3, where n is an integer greater than 1. If k is divisible by 9, which of the following MUST be divisible by 9?
A.2^n - 6
B.2^n - 2
C.2^n
D.2^n + 4
Answer: A.2^n - 6
Explanation: Given: k, M and N are integers
If k is a divisor of both N and M, then k is a divisor of N+M (and N–M and M–N)
We're told that 9 is a divisor of 2^n + 3
We also know that 9 is a divisor of9.
So, applying the above rule, 9 is a divisor of 2^n + 3 +9, and 9 is a divisor of 2^n + 3 -9= 2^n-6
A
Question: For a group of n people, k of whom are of the same sex, the (n-k)/n expression yields an index for a certain phenomenon in group dynamics for members of that sex. For a group that consists of 20 people, 5 of whom are females, by how much does the index for the females exceed the index for the males in the group?
A. 0.05
B. 0.0625
C. 0.5
D. 0.25
Answer: C. 0.5
Explanation: Index for females = (20-5)/20 = 3/4 = 0.75
Index for males = (20-15/20 = 1/4 = 0.25
Index for females exceeds males by 0.75 - 0.25 = 0.5
Answer: C
Question: 10 men working 6 hrs per day manufacture 200 shoes in 18 days. How many hours a day must 15 men work to manufacture the same 200 shoes in 12 days?
A.6
B.10
C.12
D.15
Answer: A.6
Explanation: Explanation :
Solution: Let the required number of hours be x.
More men, less hours per day (Indirect proportion)
Less days, more working hours per day (Indirect proportion)
men 15 : 10
} : : 6 : x
days 12 : 18
.'. 15*12*x = 10*18*6
=> x = 10*18*6/(15*12)
=> x = 6
Answer : A
Question: A bullet train 200 m long is running with a speed of 69 kmph. In what time will it pass a man who is running at 3 kmph in the direction opposite to that in which the bullet train is going?
A.10 sec
B.15 sec
C.12 sec
D.11 sec
Answer: A.10 sec
Explanation: A
10 sec
Speed of the bullet train relative to man = (69 + 3) kmph
= 72 *5/18 m/sec = 60/3 m/sec.
Time taken by the bullet train to cross the man = Time taken by it to cover 200 m at (60/3) m / sec
= (200*3/60) sec = 10 sec
Question: A box contains four silver coins, of which two coins have heads on both their faces, one coin has tail on both its faces and the fourth coin is a normal one. A coin is picked at random and then tossed. If head is the outcome of the toss, then find the probability that the other face (hidden face) of the coin tossed is also a head.
A.1/5
B.2/5
C.3/5
D.4/5
Answer: D.4/5
Explanation: There are four ways (2 heads in one two-headed coin and 2 heads in the other two-headed coin)
How many ways can you get heads from this entire set of coins? There are five ways (four as identified above and one from the normal coin)
Therefore probability = 4/5
Option D
Question: The average weight of a group of boys is 30 kg. After a boy of weight 33 kg joins the group, the average weight of the group goes up by 1 kg. Find the number of boys in the group originally ?
A.4
B.5
C.2
D.7
Answer: C.2
Explanation: Let the number off boys in the group originally be x.
Total weight of the boys = 30x
After the boy weighing 33 kg joins the group, total weight of boys = 30x + 33
So 30x + 33 = 31(x + 1) = > x = 2.
Answer: C
Question: If a is a positive integer, and if the units digit of a^2 is 9 and the units digit of (a+1)^2 is 4, what is the units G digit of (a+2)^2?
A.1
B.3
C.5
D.6
Answer: A.1
Explanation: I also got A. By punching in numers:
G...7^2=...9
...8^2=...4
...9^2=...1.A
Question: A train 275 metres long is running with a speed of 60 kmph. In what time will it pass a man who is running at 6 kmph in the direction opposite to that in which the train is going ?
A.5 sec
B.6 sec
C.15 sec
D.10 sec
Answer: C.15 sec
Explanation: Solution
Speed of train relative to man =(60+6) km/hr= 66km/hr
=(66x5/18) m/sec =(55/3) m/sec
∴ Time taken to pass the man = (275x3/55)sec = 15 sec
Answer C
Question: Rose and Marry each have a bag of marbles, each of which contains 4 blue marbles, 10 red marbles, and 6 white marbles. If Rose and Marry each select one marble from their respective bags, what is the probability that either Rose or Marry select a red marble?
A.3/7
B.3/4
C.1/4
D.1/8
Answer: B.3/4
Explanation: Probability that either selects a red marble,P(Either) = 1- probability that neither selects a red marble, P(Neither)
Probability that Marry selects non red = 10c1 / 20c1 = 1/2
Probability that Rose selects non red = 10c1 / 20c1 = 1/2
=> P(Either)=1- (1/2*1/2) = 1-1/4= 3/4.
Answer B.
Question: First bunch of bananas has (1/4) again as many bananas as a second bunch. If the second bunch has 3 bananas less than the first bunch, then the number of bananas in the first bunch is
A.9
B.10
C.12
D.15
Answer: D.15
Explanation: x is the no.of banana's in second bunch
first bunh banan's will be x+(1/4)x= x*5/4
If the second bunch has 3 bananas less than the first bunch
X*5/4 = x+3, X=12,
First bunch bannana's will be 15
ANSWER:D
Question: The difference between a two-digit number and the number obtained by interchanging the positions of its digits is 54. What is the difference between the two digits of that number?
A.4
B.5
C.6
D.8
Answer: C.6
Explanation: Sol.
Let the ten’s digit be x and unit’s digit be y,
Then, (10x + y) - (10y + x) = 54 ⇔ 9 (x - y) = 54
⇔ x - y = 6
Answer C
Question: In the game of Dubblefud, red chips, blue chips and green chips are each worth 2, 4 and 5 points respectively. In a certain selection of chips, the product of the point values of the chips is 16,000. If the number of blue chips in this selection doubles the number of green chips, how many red chips are in the selection?
A.1
B.2
C.3
D.4
Answer: B.2
Explanation: this is equivalent to :-
2x * 4y * 5z = 16000
y/2= z (given)
2x * 4y * 5y/2= 16000
2x * y^2 = 16000/10
2x * y^2 = 1600
now from options given we will figure out which number will divide 800 and gives us a perfect square :-
which gives us x=2 as
2* 2* y^2 =1600
y^2 = 400
y =20
Number of red chips = 2 hence B
Question: Jack and Jill work at a hospital with 2 other workers. For an internal review, 2 of the 4 workers will be randomly chosen to be interviewed. What is the probability that Jack and Jill will both be chosen?
A. 1/3
B. 1/6
C. 1/15
D. 3/8
Answer: B. 1/6
Explanation: 1/4C2=1/6.
Answer: B.
Question: . A boy has eight trousers and 10 shirts. In how many different ways can he select a trouser and a shirt?
A.80
B.87
C.90
D.120
Answer: A.80
Explanation: Explanation:
The boy can select one trouser in eight ways.
The boy can select one shirt in 10 ways.
The number of ways in which he can select one trouser and one shirt is 8 * 10 = 80 ways.
Answer: Option A
Question: If the product of 4 integers is negative, at most how many of the integers can be negative?
A.2
B.3
C.4
D.5
Answer: B.3
Explanation: The product of 4 integers is negative
Thus an odd number of integers need to be negative to have a negative product
We are asked at most how many are required.
So, the highest odd integer before 6,i.e. 3
Correct Option : B
Question: The Carson family will purchase three used cars. There are two models of cars available, Model A and Model B, each of which is available in seven colors: blue, black, red, and green. How many different combinations of three cars can the Carsons select if all the cars are to be different colors?
A.24
B.32
C.48
D.254
Answer: D.254
Explanation: I have no idea how you got 8C8, 7C6 and 4C1.
I could have understood 8C1*6C1*4C1 (I have explained why this doesn't work in the post above)
The best way to solve it is by first selecting 3 colors out of the given 4 in 4C3 ways. (say, you got black, red and green)
Now for each color, you have 2 choices - model A or B
So you select a model in 2 ways.
No of ways of selecting the 3 cars = 7C3 * 2 * 2 * 2 = 254
Well, my logic was
The number of ways of selecting r objects from n different objects is nCr.
We have 8 options and can select either of the 8 as the first - 8C8
One car is gone and one becomes a forbidden choice so we have 7 options and need to select either of the 6 as the first - 7C6
Two cars are gone and two becomes a forbidden choice so we have 6 options and need to select either of the 4 as the first - 6C4
D
Question: Pavan travelled for 11 hours. He covered the first half of the distance at 30 kmph and remaining half of the distance at 25 kmph. Find the distance travelled by Pavan?
A.388
B.266
C.288
D.300
Answer: D.300
Explanation: Let the distance travelled be x km.
Total time = (x/2)/30 + (x/2)/25 = 11 => x/60 + x/50 = 11 => (5x + 6x)/300 = 11 => x = 300 km
Answer: D
Question: Two taps can separately fill a cistern 10 minutes and 15 minutes respectively and when the waste pipe is open, they can together fill it in 18 minutes. The waste pipe can empty the full cistern in?
A.7
B.6
C.8
D.9
Answer: D.9
Explanation: 1/10 + 1/15 - 1/x = 1/18
x = 9
Answer:D
Question: A certain list of 200 test scores has an average (arithmetic mean) of 90 and a standard deviation of d, where d is positive. Which of the following two test scores, when added to the list, must result in a list of 202 test scores with a standard deviation less than d ?
A. 80 and 80
B. 80 and 85
C. 90 and 90
D. 85 and 85
Answer: C. 90 and 90
Explanation: The standard deviation of a set shows how much variation there is from the mean, how widespread a given set is. So, a low standard deviation indicates that the data points tend to be very close to the mean, whereas high standard deviation indicates that the data are spread out over a large range of values.
So when we add numbers, which are far from the mean we are stretching the set making SD bigger and when we add numbers which are close to the mean we are shrinking the set making SD smaller.
According to the aboveadding two numbers which are closest to the mean will shrink the set most, thus decreasing SD by the greatest amount.
Closest to the mean are 90 and 90 (actually these numbers equal to the mean) thus adding them will definitely shrink the set, thus decreasing SD most.
Answer: C.
Question: Mac has £ 3 more than Ken, but then Ken wins on the horses and trebles his money, so that he now has £ 2 more than the original amount of money that the two boys had between them. How much money did Mac and Ken have between them before Ken's win ?
A.22
B.27
C.13
D.55
Answer: C.13
Explanation: Let money with Ken = x. Then, money with Mac = x + £ 3.
Now, 3x = (x + x + £ 3) + £ 2 x = £ 5.
Therefore Total money with Mac and Ken = 2x + £ 3 = £ 13.
Answer: C
Question: How long does a train 150 m long traveling at 60 kmph takes to cross a bridge of 170 m in length?
A.16.5
B.19.2
C.16.4
D.16.8
Answer: B.19.2
Explanation: D = 150 + 170 = 320 m
S = 60 * 5/18 = 50/3
T = 320 * 3/50 = 19.2 sec
Answer: B
Question: Find the average of all the numbers between 6 and 34 which are divisible by 5.
A.22
B.20
C.288
D.277
Answer: B.20
Explanation: Average = (10 + 15 + 20 + 25 + 30)/5 = 100/5 = 20.
Answer: B
Question: A walks around a circular field at the rate of one round per hour while B runs around it at the rate of seven rounds per hour. They start in the same direction from the same point at 7.30 a.m. They shall first cross each other after___ minutes?
A.11 min
B.12 min
C.10 min
D.15 min
Answer: C.10 min
Explanation: Since A and B move in the same direction along the circle, so they will first meet each other when there is a difference of one round between the two.
Relative speed of A and B = 7 - 1 = 6 rounds per hour.
Time taken to complete one round at this speed = 1/6 hr = 10 min.
C
Question: A class of boys stands in a single line, One boy is 19th in order from both the ends, How many boys are there in the class ?
A.37
B.38
C.27
D.29
Answer: A.37
Explanation: Explanation:
Number of boys in the class = (18 + 1 +18) = 37
Answer: A) 37
Question: Mr. and Mrs.Ghosh have some children. Seven of them don’t eat lettuce, five of them don’t eat banana and six of them don’t eat cabbage. Exactly two of them don’t eat cabbage and lettuce, three of them don’t eat banana and cabbage, and four of them don’t eat lettuce and banana. One eats none of these. And there is no child who eats all of these.How many children are there?
A.8
B.9
C.10
D.11
Answer: C.10
Explanation: P (A U B U C) = P(A) + P(B) + P(C) - P(A ∩ B) - P(A ∩ C) - P(B ∩ C) + P(A ∩ B ∩ C)
i think using this we can find ans as
no of child = 7+5+6-2-3-4+1 = 10
ANSWER:C
Question: The last two-digits in the multiplication 122 × 123 × 125 × 127 × 129 will be
A.20
B.50
C.30
D.40
Answer: B.50
Explanation: Solution
The answer will be 50 since, (125 × 122) will give 50 as the last two digits. Answer B
Question: A bag contain 25 blue marbles and 25 purple marbles. One marble is drawn at random. What is the probability that
marble is purple?
A.1/4
B.2/3
C.1/2
D.5/3
Answer: C.1/2
Explanation: Explanation:
Total cases = 25 + 25 = 50
Favourable cases = 25
So probability = 25/50 = 1/2
Answer: C
Question: How many positive integers less than 10,000 are there in which the sum of the digits equals 5?
A.24
B.30
C.48
D.56
Answer: D.56
Explanation: Basically, the question asks how many 4 digit numbers (including those in the form 0XXX, 00XX, and 000X) have digits which add up to 5. Think about the question this way: we know that there is a total of 5 to be spread among the 4 digits, we just have to determine the number of ways it can be spread.
Let X represent a sum of 1, and | represent a seperator between two digits. As a result, we will have 5 X's (digits add up to the 5), and 3 |'s (3 digit seperators).
So, for example:
XX|X|X|X = 2111
||XXX|XX = 0032
etc.
There are 8C3 ways to determine where to place the separators. Hence, the answer is 8C3 = 56.
D
Question: A little boy is numbering his collection of flowers by placing single-digit stickers under each specimen. If the boy has 100 flowers, how many stickers does he need? (The numbers are consecutive and the number of the first flower is 1).
A.152
B.189
C.192
D.195
Answer: C.192
Explanation: For the first 9 flowers we need 9 stickers.
For the next 90 we need 2 stickers each or 180 stickers.
For the next 900 flowers we need 3 stickers each.
The first 99 flowers correspond to 189 stickers.
Subtract 99 from the total number of flowers (100).
This leaves 1 flower that uses 3 stickers each. So, multiply 1 by 3 to get 3.
Add 3 to 189 stickers to get 192 stickers.
Answer: C
Question: A furniture store owner decided to drop the price of her recliners by 20% to spur business. By the end of the week she had sold 25% more recliners. What is the percentage increase of the gross?
A.00%
B.15%
C.20%
D.25%
Answer: A.00%
Explanation: Say a recliner is actually worth $100
If she sells 100 recliners then she earns $10000
After the discount of 20%, she will earn $80 per recliner and she sells 25% more ie.,125 recliners
Hence her sales tields 125*80=$10000
Increase in sales=10000-10000=$0
So% increase = 0*100/10000 =0%
A is the answer
Question: The HCF and LCM of two numbers are 18 and 3780 respectively. If one of them is 540, then the second one is:
A.142
B.126
C.118
D.112
Answer: B.126
Explanation: Explanation:
Product of HCF1 and LCM1 = product of HCF2 and LCM2
18× 3780 = 540× HCF2
HCF2 =18 x 3780 / 540
=126
Answer: B
Question: A train 130 m long passes a man, running at 5 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is?
A.13 km/hr
B.51.8 km/hr
C.17 km/hr
D.18 km/hr
Answer: B.51.8 km/hr
Explanation: Speed of the train relative to man = (130/10) m/sec
= (13) m/sec. [(25/2) * (18/5)] km/hr
= 46.8 km/hr. Let the speed of the train be x km/hr. Then, relative speed
= (x - 5) km/hr. x - 5 = 46.8 ==> x
= 51.8 km/hr.
Answer:B