(y^n - b^n) is completely divisible by (y - b), when
Options:
(A) n is odd natural number
(B) n is even natural number
(C) n is any natural number
(D) n is prime
(E) None

For every natural number n, (y^n - b^n) is completely divisible by (y - b). So the answer is: (C).

A 240 meter long train crosses a man standing on the platform in 6 sec. What is the speed of the train?
Options:
(A) 228
(B) 144
(C) 1266
(D) 188
(E) 211

S = 240/6 * 18/5 = 144 kmph So the answer is: (B).

The average of first 10 odd numbers is?
Options:
(A) 11
(B) 10
(C) 88
(D) 176
(E) 12

Sum of 10 odd no. = 100
Average = 100/10 = 10 So the answer is: (B).

Find the least number must be subtracted from 427398 so that remaining no.is divisible by 15?
Options:
(A) 1
(B) 3
(C) 5
(D) 6
(E) 7
On dividing 427398 by 15 we get the remainder 3, so 3 should be subtracted So the answer is: (A).