The average age of a class of 20 students is 12 years. When the age of teacher is included, the average is decreased by eight months. Age of teacher is
Answers
Given : The average age of a class of 20 students is 12 years. When the age of teacher is included, the average is decreased by eight months.
To Find : Age of teacher
Solution:
Teacher age should be more than students age hence average age should increase , not decrease ,
Still 1st Solving as per given data
Students = 20
Average age = 12 Years
Total age = 20 * 12 = 240 Years
Teacher Age = N years
Total Age = 240 + N Years
Total Person = 20 + 1 = 21
New Average = (240 + n)/21
average is decreased by eight months = 8/12 years = 2/3 years
12 - 2/3 = (240 + n)/21
=> 34/3 = (240 + n)/21
=> 238 = 240 + n
=> n = -2 ( negative age not possible )
Correct data should be average is increased by eight months = 8/12 years = 2/3 years
12 + 2/3 = (240 + n)/21
=> 38/3 = (240 + n)/21
=> 266 = 240 + n
=> n = 26
Age of teacher should be 26 Years
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