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)

Download CAT 2017 Question Paper with answers and detailed solutions in PDF

CAT 2017 Questions from Quantitative Aptitude – Arithmetic

Quantitative Aptitude – Arithmetic – Averages – Ques: The average height of 22 toddlers increases by 2 inches when two of them leave this group.
Quantitative Aptitude – Arithmetic – Mixtures – Q1 : Consider three mixtures – the first having water and liquid A in the ratio 1 : 2, the second having water and liquid B in the ratio 1 : 3, and the third having water and liquid C in the ratio 1 : 4.
Quantitative Aptitude – Arithmetic – Mixtures – Q2: Bottle 1 contains a mixture of milk and water in 7 : 2 ratio and Bottle 2 contains a mixture of milk and water in 9 : 4 ratio.
Quantitative Aptitude – Arithmetic – Time and Work – Q1: Amal can complete a job in 10 days and Bimal can complete it in 8 days. Amal, Bimal and Kamal together complete the job in 4 days and are paid a total amount of Rs 1000 as remuneration.
Quantitative Aptitude – Arithmetic – Time and Work – Q2: A person can complete a job in 120 days. He works alone on Day 1. On Day 2, he is joined by another person who also can complete the job in exactly 120 days.
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Quantitative Aptitude – Arithmetic – Profit and Loss
Quantitative Aptitude – Arithmetic – Pipes and Cisterns: A tank has an inlet pipe and an outlet pipe. If the outlet pipe is closed then the inlet pipe fills the empty tank in 8 hours.
Quantitative Aptitude – Arithmetic – Ratios

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