Question

Mean age of 25 students in a class is 12. If teacher's age is included. Yhe mean age increases by 1. The teacher's age is

Answer 1

Hey there!
We use,
Mean = Sum of observations / Number of observations

Number of students = 25
Mean age = 12

Sum of ages = 25 * 12 = 300 .

Now, If one more person is added the mean increases by 1 .

So, New mean = 13 .

Sum of ages = 13 * 26 = 338 .

Teacher age = 338 - 300 = 38

Answer 2

Mean = (sum of observations)/(number of observations)

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Here,

12 = (sum of ages of 25 students)/25

12×25 = sum of ages of 25 students

300 = sum of ages of 25 students

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When teacher's age is added,

12+1 = (sum of ages of 25 students+teacher's age)/(25+1)

13 = (300+teacher's age)/26

13×26 = 300 + teacher's age

338 = 300+ teaccher's age

338-300 = teacher's age

38 years = teacher's age


I hope this will help you

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