# Thread: Probability and CDF functions

1. ## Probability and CDF functions

A pair of fair dice is tossed 8 times. Find the probability that a sum of 7 or 11 occurs AT MOST three times.
What is the probability that the first toss is a 7, given the sum of 7 or 11 occurs at most three times in eight tosses?

Find the probability that a sum of 7 or 11 occurs AT MOST three times:::
Event A= P(A)= CDF[8,8/36],3 = 0.921039

What I'm not sure how to do is the second question. The first toss being a 7 has a probability of 6/36.

In the example in class, the question had an AT LEAST statement so the second question was answered this way: 6/36 x [1-CDF[Binomial Distribution[9,10/36],3]. Should I be using this?

The AT MOST is throwing me off.

2. ## Re: Probability and CDF functions

P(7|0.92104) = 6/36*0.92104 = 0.15351

3. ## Re: Probability and CDF functions

Thanks! I was definitely over-thinking the problem. This makes sense.
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