A person spends 40% of his salary on food, 25% on house rent, 15% on entertainment and 15% on conveyance. If his savings at the end of the month is Rs. 1200, then his salary per month in rupees is:
Options:
(A) 4000
(B) 24000
(C) 8000
(D) 10000
(E) None of these
Answer and stream of consciousness: (B)
Stream of consciousness: Total expenditure = 40 + 25 + 15 + 15 = 95%
Saving = (100 - 95) = 5%
5/100 Salary = 1200, Salary = 24000 Rs.

If the given two numbers are respectively 6% and 30% of a third number, then what percentage is the first of the second ?
Options:
(A) 20%
(B) 25%
(C) 18%
(D) 30%
(E) none of these
Answer and stream of consciousness: (A)
Stream of consciousness: Here, l = 6 and m = 30
Therefore, first number = l/m x 100% of second number = 6/30 x 100% of second number = 20% of second number

A man purchases 8 pens for Rs.9 and sells 9 pens for Rs.8, how much profit or loss does he make?
Options:
(A) 15
(B) 66
(C) 88
(D) 1
(E) 12
Answer and stream of consciousness: (A)
Stream of consciousness: 90 * 10/60 = 15 kmph

10 books are placed at random in a shelf. The probability that a pair of books will always be together is ?
Options:
(A) 1/8
(B) 1/4
(C) 1/5
(D) 1/9
(E) 1/1
Answer and stream of consciousness:
(C)
Stream of consciousness: 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