# Probability and binomial distribution?

• Jan 6th 2010, 06:38 PM
Terra
Probability and binomial distribution?
Could I get some tips/advice/information to help me solve these questions?

1. Sheryl scores on 85% of her foul shots. If she has eight foul shots during a game, what is the probability that she will score on exactly seven of them?

2. Is a normal distribution a reasonable approximation for a binomial distribution with n=50 and p=0.85? Explain.

Thanks!
• Jan 6th 2010, 06:42 PM
pickslides
Quote:

Originally Posted by Terra
Could I get some tips/advice/information to help me solve these questions?

1. Sheryl scores on 85% of her foul shots. If she has eight foul shots during a game, what is the probability that she will score on exactly seven of them?

http://www.mathhelpforum.com/math-he...ility-2-a.html

Now find

$P(X=7)$ with $n = 8$ and $p = .85$
• Jan 6th 2010, 06:54 PM
pickslides
Quote:

Originally Posted by Terra

2. Is a normal distribution a reasonable approximation for a binomial distribution with n=50 and p=0.85? Explain.

Thanks!

The sample size looks a bit small for a normal approximation. Use normal dist for $n \approx 30$ or greater.

Also will $p=0.85$ give to much of a skew to use a bell shaped curve?
• Jan 6th 2010, 06:59 PM
Terra
I tried the equation for the first one and my answer is 0.3846. Is that right?
• Jan 6th 2010, 09:00 PM
mr fantastic
Quote:

Originally Posted by Terra
I tried the equation for the first one and my answer is 0.3846. Is that right?

The last decimal place should be 7 if you are rounding to four decimal places.
• Jan 7th 2010, 07:11 AM
Terra
Thanks guys! You two have been a huge help.