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Averages - December 22, 2003
The GMAT Sample Math question for the day is from the topic Averages.
Question
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?
A. 22 years
B. 30 years
C. 44 years
D. 32 years
E. None of these
The correct choice is (D) and the correct answer is 32 years.
Explanatory Answer
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 = 64/2 = 32 years.
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