[Ans] (C)
[Question] 10 books are placed at random in a shelf. The probability that a pair of books will always be together is
Options:
(A) 1/9
(B) 1/7
(C) 1/5
(D) 1/6
(E) 1/3
[CoT] 10 books can be rearranged in 10! ways consider the two books taken as a pair then number of favourable ways of getting these two books together is 9! 2!
Required probability = 1/5

[Ans] (C)
[Question] If 14m − n = p, then which of the following represents the average (arithmetic mean) of m, n, and p, in terms of m?
Options:
(A) 2m −1
(B) 4m
(C) 5m
(D) m/5
(E) 6m/5
[CoT] 14m - n = p
Add n to both sides:
14m = n + p
Add m to both sides:
15m = n + p + m
Now, divide both sides by 3
5m = (n + p + m)/3 = the average of n, p, and m

[Ans] (D)
[Question]
Anil can do a work in 12 days while Sunil can do it in 25 days. How long will they take if both work together?
Options:
(A) 10 1/10 days
(B) 18 1/10 days
(C) 7 1/10 days
(D) 8 1/10 days
(E) 9 1/10 days
[CoT] 1/12 + 1/25 = 37/300
300/37 = 8 1/10 days