Reasoning: Speed of the boat in still water = (60+100)/2 = 80 kmph. Speed of the stream = (100-60)/2 = 20 kmph
Ans: (D)
Question: The speed of a boat in upstream is 60 kmph and the speed of the boat downstream is 100 kmph. Find the speed of the boat in still water and the speed of the stream?
Options:
(A) 70, 10 kmph
(B) 35, 27 kmph
(C) 50, 60 kmph
(D) 80, 20 kmph
(E) 45, 65 kmph
Rationale: 10(11111)*4! - 10(1111)3! = 2599980
The answer: (A)
Question: What is the sum of all 5 digit numbers which can be formed with the digits 0,1,2,3,4 without repetation?
Options:
(A) 2599980
(B) 235500
(C) 923580
(D) 765432
(E) 765434
Reasoning: S = 600/40 = 15 mps
S = 3600/15 = 240 sec = 4 min
Ans: (A)
Question: A 600 meter long train crosses a signal post in 40 seconds. How long will it take to cross a 3 kilometer long bridge, at the same speed?
Options:
(A) 4 min
(B) 2 min
(C) 8 min
(D) 9 min
(E) 5 min
Rationale: If the number is divisible by 11, then the alternate digits' sum must be divisible by 11 or difference is 0. Only 1 yields such a number.
The answer: (A)
Question: The number N is 5,H48, where H represents the hundred's digit. If N is divisible by 11, what is the value of H
Options:
(A) 1
(B) 7
(C) 6
(D) 5
(E) 2
Reasoning: Since the coin is a fair coin, every toss is independent of any other toss. Hence, the probability of appearance of tail on the fifth toss is = 1/2
Ans: (B)
Question: A fair coin is tossed repeatedly. If head appears on the first four tosses, then the probability of appearance of tail on the fifth toss is.
Options:
(A) 1/7
(B) 1/2
(C) 3/7
(D) 2/3
(E) 1/3
Reasoning: Sum of all the 13 numbers = 13 * 60 = 780
Sum of the first 7 of them = 7 * 57 = 399
Sum of the last 7 of them = 7 * 61 = 427
So, the 8th number = 427 + 399 - 780 = 46.
Ans: (A)
Question: The average of 13 numbers is 60. Average of the first 7 of them is 57 and that of the last 7 is 61. Find the 8th number?
Options:
(A) 46
(B) 82
(C) 45
(D) 43
(E) 53