Arithmetic Reasoning - Study Mode
[#1] The number of boys in a class is three times the number of girls. Which one of the following numbers cannot represent the total number of children in the class ?
Correct Answer
(C) 42
Explanation
Solution: Let number of girls = x and number of boys = 3x. Then, 3x + x = 4x = total number of students. Thus, to find exact value of x, the total number of students must be divisible by 4.
[#2] A shepherd had 17 sheep. All but nine died. How many was he left with ?
Correct Answer
(C) 9
Explanation
Solution: 'All but nine died' means 'All except nine died' i.e. 9 sheep remained alive.
[#3] In a family, the father took 1/4 of the cake and he had 3 times as much as each of the other members had. The total number of family members is
Correct Answer
(C) 10
Explanation
Solution:
[#4] In three coloured boxes - Red, Green and Blue, 108 balls are placed. There are twice as many balls in the green and red boxes combined as there are in the blue box and twice as many in the blue box as there are in the red box. How many balls are there in the green box ?
Correct Answer
(D) None of these
Explanation
Solution: Let R, G and B represent the number of balls in red, green and blue boxes respectively. Then, . R + G + B = 108 ...(i), G + R = 2B ...(ii) B = 2R ...(iii) From (ii) and (iii), we have G + R = 2x 2R = 4R or G = 3R. Putting G = 3R and B = 2R in (i), we get: R + 3R + 2R = 108 ⇔ 6R = 108 ⇔ R = 18. Therefore Number of balls in green box = G = 3R = (3 x 18) = 54.
[#5] The total number of digits used in numbering the pages of a book having 366 pages is
Correct Answer
(B) 990
Explanation
Solution: Total number of digits = (No. of digits in 1- digit page nos. + No. of digits in 2-digit page nos. + No. of digits in 3- digit page nos.) = (1 x 9 + 2 x 90 + 3 x 267) = (9 + 180 + 801) = 990.