GMAT Maths | GMAT Statistics Questions

GMAT Sample Questions | Average | Arithmetic Mean

This GMAT quant practice question is a problem solving question from statistics and averages. Concept: Computing arithmetic mean of new elements added to a set of data.

Question 6: The average age of a group of 10 students was 20. The average age increased by 2 years when two new students joined the group. What is the average age of the two new students who joined the group ?

  1. 22 years
  2. 30 years
  3. 44 years
  4. 32 years
  5. None of these

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Explanatory Answer

Standard Framework
Description Number Average Sum
Initially 10 20 200
After 2 students join 12 22 264
Sum of ages of 2 new students 264 - 200 = 64 kg

The average age of a group of 10 students is 20.
Therefore, the sum of the ages of all 10 of them = 10 * 20 = 200

When two new students join the group, the average age increases by 2. New average = 22.
Now, there are 12 students.
Therefore, the sum of the ages of all 12 of them = 12 × 22 = 264

Therefore, the sum of the ages of the two new students who joined = 264 - 200 = 64

And the average age of each of the two new students = \\frac{64}{2}) = 32 years.

Choice D is the correct answer.

 

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