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JEE Main 202118 MarchMorning Shift
Exam
JEE Main
Year
2021
Date
18 March
Shift
Morning Shift
Subject
Mathematics
Chapter
Statistics

JEE Main 2021 · 18 March · Morning Shift · Mathematics · Statistics

The mean age of 25 teachers in a school is 40 years. A teacher...

The mean age of 2525 teachers in a school is 4040 years. A teacher retires at the age of 6060 years and a new teacher is appointed in his place. If the mean age of the teachers in this school now is 3939 years, then the age (in years) of the newly appointed teacher is

Options

  1. A3535
  2. B4040
  3. C2525
  4. D3030

Correct answer

A. 3535

Step-by-step solution

∑xi25=40\dfrac{∑ {x}_{i}}{25} = 40 and ∑xi−60+N25=39\dfrac{∑ {x}_{i} - 60 + N}{25} = 39

Let age of newly appointed teacher is NN

⇒1000−60+N=975⇒ 1000 - 60 + N = 975

⇒N=35⇒ N = 35 year

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