# URGENT : Probability?

• Jan 29th 2013, 11:30 AM
shakeel7
URGENT : Probability?
Simran can either take a course in Math or in Biology, if Simran takes the math course, then she will receive an A grade with probability 1/5. If she takes the Biology course she will receive an A grade with probability 1/6. Simran decides to base her decision on the flip of a fair coin. What is the probability that Simran will not get an A in Math?
• Jan 29th 2013, 11:36 AM
Kmath
Re: URGENT : Probability?
will not get an A in math means (it does not take math at all ) or (it takes math but not A)
So the probability is $\displaystyle \frac{1}{2}+\frac{1}{2}\frac{4}{5}$.
• Jan 29th 2013, 03:14 PM
HallsofIvy
Re: URGENT : Probability?
Imagine 1000 Simrans. 500 of them take math, 500 of them take biology. Of the 500 who take math, 500(1/5)= 100 receive an A. That is, of the 1000 Simrans. 100 get an A in math and 900 do not. The probability Simran does not get an A in math is 900/1000. This is, of course, the same result Kmath got.