<PRE><B>Question 306689</B>
The average age of five boys is 15 years.  A six boys joins them, making the average age 15 years and 6 months. What is the age of this sixth boy ?

the average age of 5 boys is 15 years . 
the total of their ages = 75 years

1 boy joins them

so total number of boys will be 6
the average age of 11 boys is = 15 1/2 years (31/2)

total of their ages = 6* 31/2= 91 years

total age of 6 boys - total age of 5 boys = age of 6th. boy

91-75= 16 years

Age of 6th. boy is 16 years 

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