The average of seven numbers is 21. The average of first three numbers is 19 and the average of last three numbers is 23. What is the middle number?
Options:
(A) 20
(B) 22
(C) 18
(D) 19
(E) 21
--
The total of seven numbers = 7X21 = 147
The total of first 3 and last 3 numbers is = 3 X 19+3 X 23 = 126
So, the middle number is (147 - 126 ) = 21 So the answer is: (E).
-----
A train 360 m long is running at a speed of 45 km/hr. In what time will it pass a bridge 390 m long?
Options:
(A) 40 sec
(B) 60 sec
(C) 45 sec
(D) 48 sec
(E) 50 sec
--
Speed = 45 * 5/18 = 25/2 m/sec
Total distance covered = 360 + 140 = 750 m
Required time = 750 * 2/25 = 40 sec So the answer is: (B).
-----
A person spends 40% of his salary on food, 25% on house rent, 15% on entertainment and 5% on conveyance. If his savings at the end of the month is Rs. 1500, then his salary per month in rupees is:
Options:
(A) 4000
(B) 6000
(C) 8000
(D) 10000
(E) None of these
--
Total expenditure = 40 + 25 + 15 + 5 = 85%
Saving = (100 - 85) = 15%
15/100 Salary = 1500, Salary = 10000 Rs. So the answer is: (D).
-----