probability question (1 Viewer)

[za]

i cant stand probabilty! i dunno if this question is str8 forward but it doesnt seem to clik with me
this is from the 1986 hsc paper



"there are 3 maths teachers in a school. the probability that one is female is 0.4. the probablity that one is a graduate( both male and female) is 0.7 . wat is the prbability that there are no female graduates?"

 

[Xayma]

Then why did you post?

P(NFG)=1-P(FG)
=1-.4*.7
=1-.28
=.72

 

[za]

the solution says 0.373
and theres no working out

 

[Xayma]

Oh yeah I forgot to cube it for the 3 teachers.

Yeah it works out.

 

[za]

thnx for the help

 

[Grey Council]

heh, I forgot to cube too. thats a pretty tricky question.

 

[ashtor]

why do u have to cube the answer?

 

[Xayma]

Because theres 3 teachers, my original answer would be the probability per teacher.