Wednesday, February 10, 2016

Average

The average age of 20 students in a class is 14 years. A student of age 16 leaves them and a new student joins them. Now their average age becomes 13.8 years. What is the age of the new boy?


answer::

total age of 20 students initially: 280 years
age of the student who leaves the group = 16
total age of the remaining 19 students = 280 - 16 = 264
total age of the new set of 20 students = 13.8 x 20 = 276 years
so, age of the new student = 276 - 264 = 12 years

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