q: A train 300 m long is running at a speed of 99 km/hr. In what time will it pass a bridge 195 m long?
Options:
(A) 17
(B) 18
(C) 19
(D) 20
(E) 21
a: OK... Speed = 99 * 5/18 = 55/2 m/sec
Total distance covered = 300 + 195 = 495 m
Required time = 495 * 2/55 = 18 sec
The answer is (B).

q: X can finish a work in 18 days. Y can finish the same work in 15 days. Yworked for 10 days and left the job. how many days does X alone need to finish the remaining work?
Options:
(A) 1
(B) 3
(C) 6
(D) 8
(E) 9
a: OK... Work done by X in 1 day = 1/18
Work done by Y in 1 day = 1/15
Work done by Y in 10 days = 10/15 = 2/3
Remaining work = 1 2/3 = 1/3
Number of days in which X can finish the remaining work = (1/3) / (1/18) = 6
The answer is (C).

q: The average of seven numbers is 18. The average of first three numbers is 14 and the average of last three numbers is 19. What is the middle number?
Options:
(A) 26
(B) 27
(C) 29
(D) 32
(E) 36
a:
OK... The total of seven numbers = 7X18 = 126
The total of first 3 and last 3 numbers is = 3 X 14+3 X 19 = 99
So, the middle number is (126 - 99 ) = 27
The answer is (B).