Question

in a classroom the probabilty that the teacher chooses a boy from a girl is 0.45. how many boys are there?

Answer 1

P=favorable outcome/total outcome
P of choosing boy is given which 0.45
0.45=B/20
B=9 boys

Answer 2

0.45/1 becuase 1 is 100%
0.45/1=4.5/10=45/100=9/20

9/20 chance that chooses a boy
20 people
9/20 times 20=9
9 boys