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# Aptitude Questions and Answers with Explanation for placement, MBA

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 16 If the average marks of three batches of 55, 60 and 45 students respectively is 50, 55, 60, what is the average marks of all the students? A. 53.23 B. 54.68 C. 51.33 D. 50
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Explanation

Average marks of batch1 = 50

Students in batch1 = 55

Total marks of batch1 = 55 × 50

Average marks of batch2 = 55

Students in batch2 = 60

Total marks of batch2 = 60 × 55

Average marks of batch3 = 60

Students in batch3 = 45

Total marks of batch3 = 45 × 60

Total students = 55 + 60 + 45 = 160

Average marks of all the students

= [(55×50)+(60×55)+(45×60)]160

= [ 275+330+270 ]/16 .

= 875/16 .

= 54.68.

 17 The average age of husband, wife and their child 3 years ago was 27 years and that of wife and the child 5 years ago was 20 years. What is the present age of the husband? A. 40 B. 32 C. 28 D. 30
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Explanation

Let the present age of the husband = h
Present age of the wife = w
Present age of the child = c
3 years ago, average age of husband, wife and their child = 27
=> Sum of age of husband, wife and their child before 3 years = 3 × 27 = 81
=> (h-3) + (w-3) + (c-3) = 81
=> h + w + c = 81 + 9 = 90           --------------- equation(1)

5 years ago, average age of wife and child = 20
=> Sum of age of wife and child before 5 years = 2 × 20 = 40.
=> (w-5) + (c-5) = 40
=> w + c = 40 + 10 = 50                     --------------- equation(2)
Substituting equation(2) in equation(1)
=> h + 50 = 90
=> h = 90 - 50 = 40
i.e., Present age of the husband = 40

 18 There are two divisions A and B of a class, consisting of 36 and 44 students respectively. If the average weight of divisions A is 40 kg and that of division b is 35 kg. What is the average weight of the whole class? A. 38.25 B. 37.25 C. 38.5 D. 37
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Explanation

Total weight of students in division A = 36 × 40

Total weight of students in division B = 44 × 35

Total students = 36 + 44 = 80

Average weight of the whole class :-

= [(36×40)+(44×35)]/80

= [(9×40)+(11×35)]/20

= [(9×8)+(11×7)]/4

= [72+77]/4

= 149/4

= 37.25

 19 A batsman makes a score of 87 runs in the 17th inning and thus increases his averages by 3. What is his average after 17th inning? A. 39 B. 35 C. 42 D. 40
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Explanation

Let the average after 17 innings = x
Total runs scored in 17 innings = 17x
Average after 16 innings = (x-3)
Total runs scored in 16 innings = 16(x-3)
Total runs scored in 16 innings + 87 = Total runs scored in 17 innings
=> 16(x-3) + 87 = 17x
=> 16x - 48 + 87 = 17x
=> x = 39

 20 A student needed to find the arithmetic mean of the numbers 3, 11, 7, 9, 15, 13, 8, 19, 17, 21, 14 and x. He found the mean to be 12. What is the value of x? A. 12 B. 5 C. 7 D. 9
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Explanation

=> (3+11+7+9+15+13+8+19+17+21+14+x) / 12 = 12.

=> (137+x) / 12 =12.

=> 137+x =144 .

=> x=144−137=7.

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