Reasoning: Speed = 63 * 5/18 = 35/2 m/sec
Total distance covered = 495 +240 = 735 m
Required time = 700 * 2/35 = 42 sec
Ans: (D)
Question: A train 495 m long is running at a speed of 63 km/hr. In what time will it pass a bridge 240 m long?
Options:
(A) 39
(B) 40
(C) 41
(D) 42
(E) 43
Rationale: Total age of students is 12X8 = 96 Years
Total age inclusive of teacher = 13X (8+1) = 117
So, Teacher's age is 117-96 = 21 Yrs
There is a shortcut for these type of problems
Teacher's age is 8+(13X1) = 21 Years
The answer: (C)
Question: The average age of a class of 12 students is 8 yrs. if the teacher's age is also included, the average increases by one year. Find the age of the teacher
Options:
(A) 30 Years
(B) 31 Years
(C) 21 Years
(D) 34 Years
(E) 49 Years
Reasoning: T = 40/36 * 18/5 = 4 sec
Ans: (B)
Question: In what time will a railway train 40 m long moving at the rate of 36 kmph pass a telegraph post on its way?
Options:
(A) 3 sec
(B) 4 sec
(C) 5 sec
(D) 6 sec
(E) 7 sec
Rationale: Speed = 60*(5/18) m/sec = 50/3 m/sec
Length of Train (Distance) = Speed * Time
(50/3) * 12 = 200 meter
The answer: (B)
Question: A train running at the speed of 60 km/hr crosses a pole in 12 seconds. Find the length of the train.
Options:
(A) 225 meter
(B) 200 meter
(C) 250 meter
(D) 190 meter
(E) 180 meter
Reasoning: 36^2 = 6*6*6*6 = 2^4*3^4
Total factors = (4+1)*(4+1) = 6*4 = 24
Ans: (C)
Question: How many factors does 35^2 have?
Options:
(A) 2
(B) 8
(C) 24
(D) 25
(E) 26
Reasoning: Distance traveled by Eddy = 510 km
Time taken by Eddy = 3 hours
Average speed of Eddy = 510/3 = 170 km/hour
Distance traveled by Freddy = 300 km
Time taken by Freddy = 4 hours
Average speed of Freddy = 300/4 = 75 km/hour
Ratio of average speed of Eddy to Freddy = 170/75 = 34/15
Ans: (E)
Question: Eddy and Freddy start simultaneously from city A and they travel to City B and City C respectively. Eddy takes 3 hours and Freddy takes 4 hours to complete the journey. If the distance between City A and City B is 510 kms and City A and City C is 300 kms. What is the ratio of their average speed of travel? (Eddy: Freddy)
Options:
(A) 8/3
(B) 3/8
(C) 8/5
(D) 5/8
(E) 34/15