Question

Very unsure on this one... please help. ill give medal and fan (: posting below.

Answer 1

Suppose Q and R are independent events. Find P(Q and R) if P(Q) = \[\frac{ 7 }{ 15}\] and P(R) = \[\frac{ 4 }{ 7 }\]

Answer 2

In general, the probability of events Q and R happening is P(Q|R) * P(R). If Q and R are independent, the P(Q|R) = P(Q). So, with this independence assumption, we simply have:

P(Q & R) = P(Q) * P(R)

Answer 3

so i add 0.32 and 0.19?

Answer 4

No, don't add; multiply.

In words, the probability of Q and R happening is the probability of Q happening times the probability of R happening.

Answer 5

so multiply 0.32 and 0.19 and then do what?

Answer 6

how are you getting 0.32 and 0.19 ?

Answer 7

Oh yeah, that's a good point. Those probabilities for Q and R do not correspond to the probabilities given in your question.

For instance, P(Q) is given as 7/15.

Answer 8

oops sorry i was looking at a similar question with different values

Answer 9

Ahhh, then yes, you have the right idea, simply multiply them together.

Answer 10

and after i multiply them what do i do?

Answer 11

@jim_thompson5910 Thanks for noticing that!

Answer 12

np and keep things as fractions to avoid roundoff error

Answer 13

After multiplying them, then you are done.

P(Q & R) = P(Q) * P(R)

Answer 14

Ohhh okay thats easy thanks (:

Answer 15

And, as @jim_thompson5910 stated, multiply them as fractions. There is no need to convert them to an approximate decimal form. If you'd like, you can try to do that here.

Answer 16

Okay I got 4/15 (:

Answer 17

Good work! :)