A teacher gave her class two exams; 60% of the class passed the second exam, but only 48% of the class passed both exams. What percent of those who passed the second exam also passed the first exam?

Question

katecc379 · Answer

@Hero

hero · Answer

one moment

katecc379 · Answer

okay

hero · Answer

What concepts are you currently studying in class that might be related to this problem?

katecc379 · Answer

conditional probability

hero · Answer

There's a formula for that you should apply for this.

katecc379 · Answer

is it 80%?

hero · Answer

$$P(A|B) = \dfrac{P(A \cap B}{P(B)}$$

hero · Answer

Take that back. All signs point to that the answer is 80%. I calculated it three different ways and got 80%

katecc379 · Answer

i don't understand

katecc379 · Answer

ok cool

katecc379 · Answer

would this be .171

hero · Answer

Once again, apply conditional probability formula.

katecc379 · Answer

okay i did I'm asking you to check my answer

katecc379 · Answer

@Hero

hero · Answer

If you used the conditional probability formula, it's probably wrong. The probability of taking an English class does not represent P(B)

katecc379 · Answer

okay can you please check my answer that is all i am asking

hero · Answer

Explain how you arrived at your answer. What formulas did you use?

katecc379 · Answer

don't know how to type it on my computer its in my notebook

katecc379 · Answer

wait is it .49

hero · Answer

0.49 is the probability of taking an English class.

hero · Answer

Explaining how you arrived at the answer you got is the path to figuring out where you are and what the correct steps are.

katecc379 · Answer

it is .171

hero · Answer

I just wanted you to explain how you arrived at your answer.