Help with a probability question please!!?!?!?

The final test for a stats test is based on 18 different topics and the instructor announces in the class that the exam will have 6 question from six different topics. A student decides to only study 12 topics. What is the probability that from the topics the student studies:

a).No questions are asked?

b).Two questions are asked?

c).All six questions are asked?

Top 2 Answers

A few days ago

Merlyn

Favorite Answer

Let X be the number of question in a topic area the student studied.

X has the binomial distribution with n = 6 trials and success probability p = 12/18 = 2/3

In general, if X has the binomial distribution with n trials and a success probability of p then

P[X = x] = n!/(x!(n-x)!) * p^x * (1-p)^(n-x)

for values of x = 0, 1, 2, …, n

P[X = x] = 0 for any other value of x.

P(X = 0) = 6!/(0! (6 – 0)!) * (2/3) ^ 0 * (1 – 2/3) ^ (6-0)

= 0.001371742

P(X = 2) = 6!/(2! (6 – 2)!) * (2/3) ^ 2 * (1 – 2/3) ^ (6-2)

= 0.082304527

c) P(X = 6) = 6!/(6! (6 – 6)!) * (2/3) ^ 6 * (1 – 2/3) ^ (6-6)

= 0.087791495

A few days ago

norcekri

This is homework *help* — all you’ve done so far is to post the entire problem. Where are you stuck? If it’s simply with the application, think of the 18 topics as colored balls in a bag. Think of the six the student studies as bright red balls; the other twelves are a painfully dull gray. Now can you translate the problem into something like you’ve seen in your textbook? If not, write again and let us know where you’re stuck.

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Help with a probability question please!!?!?!?

Help with a probability question please!!?!?!?

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