Question

There are 30 boys and average age is 10 and 40 girls and average age is 8 find total average

Answer 1

$10 \times 30 = 300 \: \: average \: age \: of \: boys \:$
$40 \times 8 = 320 \: average \: age \: of \: girls \:$
The total average age is 300+320=620