Question

at a school fair 70% of people are under 16 years old. one third of the people remaining are teachers.if there are 21 teachers at the fair total?

Answer 1

let number of people at the fair be x.

As per the statement:

70% of people are under 16 years old

⇒
`x * 70 \% = x * (70)/(100) = (70x)/(100) =(7x)/(10)`

Remaining number =
`x - (7x)/(10) = (10x-7x)/(10) = (3x)/(10)`

Since, one third of the people remaining are teachers

⇒Number of teachers at fair =
`(1)/(3) * (3x)/(10) = (x)/(10)`

Also, it is given that the number of teachers at the fair are 21.

hence,
`(x)/(10) = 21`

Multiply both sides by 10 we get;

x = 210

Therefore, total number of people at fair are. 210 people