Question

In a group of $20$ singers and $40$ dancers, $20\%$ of the singers are less than $25$ years old and $40\%$ of the entire group are under $25$ years. What percentage of dancers are under $25$ years?

Answer 1

There are total $20$ singers.

$\frac{20}{100}\times 20=4$singers are less than $25$ years.

Total number of singers and dancers=$20+40=60$

$\frac{40}{100}\times 60=24$ people are less than $5$ years.

$\therefore$ Numner of dancers less than $25$ year old=$24-4=20$

$\therefore$ Percentage of the dancers are under $25$ years=$\frac{20}{40}\times 100=50\%$