We have to calculate age of the youngest boy.
Here the average age is 15 years
we know that;
\[ Average = \frac{Sum Of Terms}{Total Number Of Terms} \]
Here if consider average age of boys,
number of terms means number of boys which is 3
and
sum of numbers means – sum of ages of three boys !
i-e the above formula will look like;
\[ 15 = \frac{Sum Of Ages Of Three boys}{3} \]
So, we get;
Sum of ages of three boys = \( 15\times 3=45 \)
i-e total age of three bys = 45
We use share formula here, which is ;
\[ Share = \frac{Total}{Sum Of Ratios}\times Ratio \]
Now given that their ages are in the ratio; 3:5:7
Sum of ratios \( 3+5+7=15 \)
So
first boy’s share:\( = \frac{45}{15}\times 3=9 \)
second boy’s share:\( = \frac{45}{15}\times 5=15 \)
third boy’s share:\( = \frac{45}{15}\times 7=21 \)
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