G Math help :) (1 Viewer)

[face34]

I'm doing papers and have troubles with this question

 

[Carrotsticks]

If only one of them is successful, this means we can only either have:

- Lou successful, then Ali not successful

- Lou unsuccessful, then Ali successful

The first one has probability 0.7 x 0.4 = 0.28 by following the tree diagram.

Similarly, the second one has probability 0.3 x 0.6 = 0.18

Adding these two gives 0.28 + 0.18 = 0.46 and so the answer is (D).

 

[face34]

another question if anyone can please help that would be great.

 

[face34]

Thanks carrotsticks

 

[qwerty44]

another question if anyone can please help that would be great. View attachment 25654

If the results were accurate, that means that you need to add:

-The number of people with the flu and the test indicated so +

-The number of people without the flu and the test indicated so.

So 72+256=328. Then to find as % put it over 347, which is equal to 94.52449568%, rounded to 95%. So (C)

 

[face34]

thanks