Question

The probability of Anna, Bianca and Cilem passing a geography test is 0.25, 0.5 and 0.4 respectively. The probability that only two girls will past the next geography test is?

Answer 1

If Cilem is a boy.
0.25*0.5=1/8 or 0.125

Answer 2

P (A and B) = P(a) * P(B) = 0.25 * 0.5 = 0.125

Answer 3

the answer is 0.275

Answer 4

Assuming Cilem is also a girl... then we have a tricky problem that only 2 out of the three pass the test, which means we need to examine all permutations.

Call the three A, B and C we have three permutations:

A passes, B passes, C fails
A passes, C passes, B fails
B passes, C passes, A fails

We are given the chances of passing. The chances of failing a just 1 - chance of passing.

Using ! for not passing we get:
AxBx!C = .25 x .5 x .6 = .075
AxCx!B = .25 x .4 x .5 = .05
BxCx!A = .5 x .4 x .75 = .15

Adding we get .275

Answer 5

oh i see thank you very much

Answer 6

Thanks fo the medal!

Answer 7

nw:)