80% of the company staff is male. 20% of the company staff is female.
57% of the staff's highest qualification is Ordinary Level. 32% of the staff's highest qualification is Advanced Level. Other's are graduates.
40% of the female staff's highest qualification is Ordinary Level. 45% of the female staff's highest qualification is Advanced Level. Other females are Graduates.
Now we choose a random person from the staff.
What I did
$80$ males + $20$ females
$40$ percent of $20$ females is $8$ OL females $45$ percent of $20$ females is $9$ AL females $15$ percent of $20$ females is $3$ Graduate females
Then $57-8$ = $49$ are up to OL males And $32-9$=$23$ are up to AL males. So $11-3$=$8$ are up to Graduate males.
- What is the probability of choosing a female whose highest qualification is Ordinary Level?
$$\frac{20}{100} \times \frac{40}{100} = \frac{8}{100}$$
- What is the probability of choosing a male whose highest qualification is Ordinary Level?
$$ \frac{49}{100}$$
- What is the probability of choosing a graduate, given that it is a male?
$$ \frac{8}{80}$$
4)What is the probability of choosing a female, given that it is a non-graduate staff member?
$$ \frac{\frac{17}{100}}{\frac{89}{100}}=\frac{17}{89}$$
Am I doing something wrong?
My book answers are not the same except for first question.