Question

The average age of 80 girls is 15 years and the average age of x boys is 20 years. If the average age of all is 16 years, find the number of boys (x).​

Answer 1

Total ages of 80 boys = 15 x 80

= 1200 yrs.

Total age of 25 boys = 14 x 25

= 350 yrs

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Average age of remaining boys =

= 1200 - (240+350) / 80 - (25+16) =610/41

X (boys)= 15.25 yrs.