JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Statistics

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The mean age of 25 teachers in a school is 40 years. A teacher retires at the age of 60 years and a new teacher is appointed in his place. If the mean age of the teachers in this school now is 39 years, then the age (in years) of the newly appointed teacher is:

Answer: 35

Solution

The total age of the

25

teachers is

25 \times 40 = 1000

years. Replacing the retiring teacher by one aged

x

changes the total to

1000 - 60 + x

, and the new mean gives

\frac{1000 - 60 + x}{25} = 39

940 + x = 975

. The newly appointed teacher is

35

years old.

JEE Main · 2021 · 18 Mar 2021 · Shift 1 · Integer answer

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