Question

What is the probability that a randomly chosen person is female or likes McDonalds?

Answer 1

@kropot72

Answer 2

Man, I was having trouble on this question, and when I saw you online, you made my day :D

Answer 3

I don't know where to start on this one, its complicating. I know when its "or" I have to find the sum. But it still won't give me the answer.

Answer 4

Have you completed the table by finding the sums of the rows and the columns? This is the first step.

Answer 5

Yes, I know the sum of the whole table is 100, and I know that for females is 55, and that for mcdonald is 40

Answer 6

Good. So we know the following:
P(F) = 0.55
P(McD) = 0.4
Now you need to find the intersection of 'female' and 'likes McDonalds' on the table.

Answer 7

.55/100 + .40/100 (

Answer 8

So far so good. Now you need to find the intersection of 'female' and 'likes McDonalds' on the table.

Answer 9

And I have to subtract them by p(female and from mcdonald) Which I think is .20/100

Answer 10

Is that it, because in my book, it says the answer is 3/4, and I don't know how they came up with this answer

Answer 11

The formula needed is:
\[\large P(A \cup B)=P(A)+P(B)-P(A \cap B)\]

Answer 12

I'm familiar with this formula, but is p(female and from mcdonald)=.20/100 right? I just want to make sure

Answer 13

\[\large P(Female\ \cap McDonalds)=\frac{20}{100}=0.2\]

Answer 14

Yeah, got it, I accidentally placed the decimals and it kept giving me the wrong answer.

Answer 15

Thanks bud :D

Answer 16

You're welcome :)