Question

The average age of class is 12. If the age of piano teacher is also included the average age goes up to 13. If the ages of piano teacher and geography teacher who is 38 yrs old are included the average age further goes up by 1. what is the number of students in the class.

Answer 1

mean =sum of the angle of 25students /25

here 12 =sum/25

sum =300

now teacher age is added so

=300+x/26

13*26=300+x

x=388-300

x=38

the answer is 38

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