Rationale: The total of seven numbers = 7X18 = 126
The total of first 3 and last 3 numbers is = 3 X 14+3 X 16 = 90
So, the middle number is (126 - 90 ) = 36
The answer: (C)
Question: The average of seven numbers is 18. The average of first three numbers is 14 and the average of last three numbers is 16. What is the middle number?
Options:
(A) 27
(B) 29
(C) 36
(D) 34
(E) 35
Reasoning: 1 to 11 = 11 * 50 = 550
1 to 6 = 6 * 49 = 294
6 to 11 = 6 * 52 = 312
6th = 294 + 312 550 = 56
Ans: (C)
Question: The average age of 11 boys is 50, if the average age of first six boys is 49 and that of the last six is 52. Find the boy age?
Options:
(A) 48
(B) 50
(C) 56
(D) 62
(E) 64
Rationale: Area of an equilateral triangle = 3/4 S2
If S = 18, Area of triangle = 3/4 * 18 * 18 = 813 cm2;
The answer: (C)
Question: What is the are of an equilateral triangle of side 18 cm?
Options:
(A) 663 cm2
(B) 743 cm2
(C) 813 cm2
(D) 645 cm2
(E) 143 cm2
Reasoning: Speed of the boat in still water = (100+120)/2 = 110 kmph. Speed of the stream = (120-100)/2 = 10 kmph
Ans: (C)
Question: The speed of a boat in upstream is 100 kmph and the speed of the boat downstream is 120 kmph. Find the speed of the boat in still water and the speed of the stream?
Options:
(A) 70, 10 kmph
(B) 35, 27 kmph
(C) 110, 10 kmph
(D) 45, 55 kmph
(E) 45, 65 kmph
Rationale: Work done by X in 1 day = 1/20
Work done by Y in 1 day = 1/15
Work done by Y in 9 days = 9/15 = 3/5
Remaining work = 1 3/5 = 2/5
Number of days in which X can finish the remaining work = (2/5) / (1/20) = 8
The answer: (D)
Question: X can finish a work in 20 days. Y can finish the same work in 15 days. Yworked for 9 days and left the job. how many days does X alone need to finish the remaining work?
Options:
(A) 3
(B) 5
(C) 6
(D) 8
(E) 9
Rationale: 11 is the only prime number or odd number in the series.
The answer: (E)
Question: Find the wrong number below mentioned series
11,150,280,560,800
Options:
(A) 800
(B) 560
(C) 280
(D) 150
(E) 11