In this problem, we will approximate a binomial dis- tribution by a normal distribution. From looking at the pmfs of the binomial distribution, for large values of n the histogram of the binomial pmf looks “bell-shaped”. It turns out that the normal distribution is a good approximation for the binomial approximation for large n. It also works for small n as long as p is not too far from 0.5. For convenience, we will let q = 1 − p.

College Algebra
7th Edition
ISBN:9781305115545
Author:James Stewart, Lothar Redlin, Saleem Watson
Publisher:James Stewart, Lothar Redlin, Saleem Watson
Chapter9: Counting And Probability
Section9.3: Binomial Probability
Problem 2E: If a binomial experiment has probability p success, then the probability of failure is...
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Please help with problems a, b, and c: 

In this problem, we will approximate a binomial dis- tribution by a normal distribution. From looking at the pmfs of the binomial distribution, for large values of n the histogram of the binomial pmf looks “bell-shaped”. It turns out that the normal distribution is a good approximation for the binomial approximation for large n. It also works for small n as long as p is not too far from 0.5. For convenience, we will let q = 1 − p.

(a) Let X~ Binomial (25, 0.4). Compute P(X = 10).
(b) We will approximate with a normal random variable. Let Y
be a normal random variable with the same mean and variance
as X. Compute P(9.5 ≤ Y ≤ 10.5). We will use this as an
approximation for P(X = 10).
(c) Briefly explain why we used the event (9.5 ≤ Y ≤ 10.5) to
approximate the event (X = 10).
Transcribed Image Text:(a) Let X~ Binomial (25, 0.4). Compute P(X = 10). (b) We will approximate with a normal random variable. Let Y be a normal random variable with the same mean and variance as X. Compute P(9.5 ≤ Y ≤ 10.5). We will use this as an approximation for P(X = 10). (c) Briefly explain why we used the event (9.5 ≤ Y ≤ 10.5) to approximate the event (X = 10).
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