Question

average age of five boy 13 year one more boy joins them and the average age become 12 year the age of the boy how joins the last is​

Answer 1

• 5 boys = 13 × 5 = 65 years
• when 1 boy in added ,
• 6 boys = 6×12 = 72 years
• age of last boy joined = 72 - 65 = 7 years

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Answer 2

Given:-

• Average age of 5 boys = 13 years where one more boy joins in 5 boys
• Average age of 6 boys = 12 years

To Find:-

• What was the age of the last boy who joins ?

Solution:-

Let the ages of 6 boys be A,B,C,D,E,F

Then,

• Average age of 5 boys = 13 years

➤ A+B+C+D+E / 5 = 13

➤ A+B+C+D+E = 13 × 5

➤ A+B+C+D+E = 65 years

Now, Average age of 6 boys is 12 years

➤ A+B+C+D+E+F/6 = 12

➤ A+B+C+D+E+F = 12 × 6

➤ A+B+C+D+E+F = 72 years

Subtracting the average age of 5 boys with average age of 6 boys,to find the age of last boy

➤ F = 72 - 65

➤ F = 7 years

Therefore,

• The age of last boy = F = 7 years

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