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View Full Version : Help solving binomial distributions


smrtboy90
Oct 5, 2010, 11:52 AM
Does anyone know the solutions to these distributions?

A survey found that 25% of pet owners had their pets bathed professionally rather than do it themselves. If 18 pet owners are randomly selected, find the probability that exactly 5 people have their pets bathed professionally.

Approximately 10.3% Of American High School Students Drop Out Before Graduation. Choose 10 Students Entering High School At Random. Find the probability that at least 6 will graduate

Thanks

Unknown008
Oct 6, 2010, 07:01 AM
From your previous thread (https://www.askmehelpdesk.com/mathematics/statistics-questions-513802.html), I'll take this as a follow up.

1. n = 18, p = 0.25, q = 0.75

Let X be the event that a pet owner had their pets bathed professionally.

X ~ B(18, 0.25)

Find P(X = 5) using the equation I gave you in your previous thread.

2. Practically the same thing here.

n = 10, p = 0.103, q = 0.897

Let X be the number who drop out.

Then you need to find P(at\ least\ 6\ graduate) which means 6, 7, 8, 9 or 10 who graduate.

Now, you if X represent those that drop out, and you need at least 6 graduates, it means that you need to have 4, 3, 2, 1 or 0 drop outs, which is P(X \leq 4)

P(X\leq 4) = P(X = 4) + P(X = 3) + P(X = 2) + P(X = 1) + P(X = 0)

Post what you get! :)