Ques: The average of 9 observations was 9, that of the 1st of 5 being 10 and that of the last 5 being 8. What was the 5th observation?
Options:
(A) 9
(B) 8
(C) 7
(D) 6
(E) 3
Ans: (A)
CoT: 1 to 9 = 9 * 9 = 81
1 to 5 = 5 * 10 = 50
5 to 9 = 5 * 8 = 40
5th = 50 + 40 = 90 81 = 9

Ques: How much more would Rs.20000 fetch, after two years, if it is put at 20% p.a. compound interest payable half yearly than if is put at 20% p.a. compound interest payable yearly?
Options:
(A) 482
(B) 337
(C) 277
(D) 288
(E) 2781
Ans: (A)
CoT: 20000(11/10)4 - 20000(6/5)2 = 482

Ques: Look at this series: 1.25, 7.5, ____, 270, 1620, ... What number should fill the blank?
Options:
(A) 50
(B) 65
(C) 45
(D) 55
(E) 40
Ans: (C)
CoT: This is a simple multiplication series. Each number is 6 times greater than the previous number.

Ques: 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
Ans: (B)
CoT: Total expenditure = 40 + 25 + 15 + 15 = 95%
Saving = (100 - 95) = 5%
5/100 Salary = 1200, Salary = 24000 Rs.