Question

A school employs 75 teachers. The following table summarises their length of service at the school,

Answer 1

There are

$12+20+13=45$

female teachers, and

$8+15+7=30$

male teachers.

This means that, out of a total of 75 teachers, 45 are female, leading to a probability of

$\dfrac{45}{75}=\dfrac{3}{5}$

of selecting a female teacher.

If we restrict to those with more than 8 years service, there are 13 female teachers and 7 male teachers.

So, out of a total of 21 teachers, there are 13 female teachers, leading to a probability of

$\dfrac{13}{21}$

of selecting a female teacher.