Question

The a verage age of 3sisters is15if the ages of 2sisters are12and15the age of third sister is

Answer 1

Here your answer✍️

AVERAGe age of 3 sisters=15
1st Sister age=12 years
2nd sister age=15years
3rd sister age=??

Let Third Sister Age=X years

$Average = \frac{total \: sum \: of \: numbers}{total \: number}$
$\frac{12 + 15 + x}{3} = 15 \\ = \frac{27 + x}{3} = 15 \\ = 27 + x = 15 \times 3 \\ = x = 45 - 27 \\ = x = 18$
Third Sister age➡️18 years