Rationale: Speed = 60 * 5/18 = 50/3 m/sec
Length of the train = speed * time = 50/3 * 6 = 100 m
The answer: (E)
Question: A train running at the speed of 60 km/hr crosses a pole in 6 sec. What is the length of the train?
Options:
(A) 118
(B) 150
(C) 277
(D) 258
(E) 100
Reasoning: Whenever you are asked to find the number of digits, try to bring the number in multiples of 10. This way, we can wasily calculate the umber of 0's through the powers of 10
50^8 8^3 11^2 x 10^2 = (5^2*2)^8*2^9*11^2x 10^2 = 5^16*2^17*11^2 x10^2 = 2*11^2*10^16x10^2 = 242*10^18
Hence we would have 16 trailing 0's and the three digits from 242
Total digits = 3 + 18 = 21
Ans: (C)
Question: How many digits are in the number 50^8 8^3 11^2 x 10^2?
Options:
(A) 22
(B) 20
(C) 21
(D) 18
(E) 17
Rationale: Probability that trouser is not grey = 2/3
Probability that shirt is not grey = 3/4
Required probability = 2/3 x 3/4 = 1/2
The answer: (A)
Question: In wardrobe Karan has 3 trousers. One of them is grey the 2nd blue and the 3rd brown. In his wardrobe he also has 4 shirts. One of them is grey and the other 3are white. He opens his wardrobein the dark and pick out one shirttrouser pair without examination the color. What is the likelihood that neither the shirt nor the trouser is grey?
Options:
(A) 1/2
(B) 2/3
(C) 4/5
(D) 6/11
(E) 4/5
Reasoning: Average = (76 + 65 + 82 + 67 + 85)/5 = 375/5 = 75.
Ans: (A)
Question: Dacid obtained 76, 65, 82, 67 and 85 marks (out of 100) in English, Mathematics, Physics, Chemistry and Biology. What are his average marks?
Options:
(A) 75
(B) 45
(C) 23
(D) 28
(E) 96
Rationale: 4/9 P = (P*R*R)/100
R = 20/3 = 6 2/3%
The answer: (A)
Question: The simple interest on a sum of money is 4/9 of the principal and the number of years is equal to the rate percent. Find the rate and the time?
Options:
(A) 6 2/3%
(B) 6 2/8%
(C) 6 9/3%
(D) 6 2/3%
(E) 6 2/1%
Rationale: S = 240/16 * 18/5 = 54 kmph
The answer: (C)
Question: A train 240 m in length crosses a telegraph post in 16 seconds. The speed of the train is?
Options:
(A) 22
(B) 71
(C) 54
(D) 77
(E) 99