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Two years ago the mean age of 40 people was 11 years. Now a person left the group
and the mean age has changed to 12 years. Find the age of the person who left the group.
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Answer:
The age of the person left = 52 years
Step-by-step explanation:
Two years ago, the mean age of 40 people was 11 years.
Therefore, two years ago, the sum of the ages of 40 people was:
11x40 years = 440 years.
The sum of the current ages of those 40 people:
= (440 + 40x2) years [since each person's age has been increased by 2 years]
= 520 years
Now a person left the group and the mean age has changed to 12 years.
Therefore, sum of the current age of the 39 remaining people in the group:
= 39x12 years = 468 years
Therefore, the age of the person left = (520 - 468) years = 52 years
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