Reasoning: The number of single digit numbers = 2
The number of 2 digit numbers = 2 3 = 6
The number of 3 digit numbers = 2 3 3 = 18
The number of 4 digit numbers = 2 3 3 3 = 54
The number of 5 digit numbers = 2 3 3 3 3 = 162
The number of 6 digit numbers = 2 3 3 3 3 3 = 486
Therefore, the total numbers = 728
Ans: (D)
Question: How many numbers can be made with digits 0, 7, 8 which are greater than 0 and less than a million?
Options:
(A) 496
(B) 486
(C) 1084
(D) 728
(E) 628
Rationale: Let the boys are X, then girls are 7X, total = X+7X = 8X
So it should be multiple of 8, 30 is not a multiple of 8.
The answer: (C)
Question: The no. of girls in a class are seven times the no. of boys, which value cannever be the of total students?
Options:
(A) 10
(B) 25
(C) 30
(D) 45
(E) 50
Reasoning: Speed downstream = d/t = 90/(2 1/2) = 36 kmph
Speed upstream = d/t = 45/(2 1/2) = 18 kmph
The speed of the stream = (36 - 18)/2 = 9 kmph
Ans: (C)
Question: A man rows his boat 90 km downstream and 45 km upstream, taking 2 1/2 hours each time. Find the speed of the stream?
Options:
(A) 5 kmph
(B) 7 kmph
(C) 9 kmph
(D) 8 kmph
(E) 1 kmph
Rationale: Given Exp. = (a3 + b3) = (a + b) = (666 + 555) = 1221(a2 - ab + b2)
The answer: (D)
Question: Solve:-
666 x 666 x 666 + 555 x 555 x 555 = ?(666 x 666 - 666 x 555 + 555 x 555)
Options:
(A) 888
(B) 333
(C) 555
(D) 1221
(E) 889
Reasoning: 1/3: 1/7: 1/1 = 7:3:21
Ans: (E)
Question: The inverse ratio of 3: 7: 1 is?
Options:
(A) 2:3:7
(B) 2:3:9
(C) 2:3:2
(D) 2:3:6
(E) 2:3:1
Reasoning: One day work of A and B = 1/2
One day work of B and C = 1/6
One day work of C and A = 1/8
2(A + B + C) = 1/2 + 1/6 + 1/8
2(A + B + C) = 19/24
(A + B + C) = 19/48
Number of days required = 48/19 days.
Ans: (B)
Question: A and B can do a work in 2 days, B and C in 6 days and C and A in 8 days. In how many days will the work be completed, if all three of them work together?
Options:
(A) 12/28
(B) 48/19
(C) 16/48
(D) 18/48
(E) 12/64