Quantitative Aptitude – Arithmetic – Averages – A class consists of 20 boys
Quantitative Aptitude – Arithmetic – Averages
Question
A class consists of 20 boys and 30 girls. In the mid-semester examination, the average score of the girls was 5 higher than that of the boys. In the final exam, however, the average score of the girls dropped by 3 while the average score of the entire class increased by 2. The increase in the average score of the boys is
A) 9.5
B) 10
C) 4.5
D) 6
Answer
Option (A)
Solution
As per CAT 2017 – Quantitative Aptitude – Arithmetic – Averages, we can see that
Score of girls = x
Score of boys = y
As per the question, x/30 = y/20 + 5
Average of class = (x + y)/ 50
New score of girls = x’
New score of boys = y’
x/30 – 3 = x’/30
(x’ + y’)/50 = (x + y)/50 + 2
x’ = x – 90
On solving we get, y’ = y + 190
New average of boys = (y + 190)/20 = y/20 + 9.5
So, average of boys increases by 9.5
Option (A)
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