Question

7. An urn contains four black and eight white balls. A sample of five balls is selected from the urn repeatedly, each time with replacement of the selected balls (thus restoring the urn to its original state). Let E be the event that the selected sample contains at most two white balls. (a) Find the probability of E (b) What is the expected number of selections until E happens? Name (c) What is the probability that E happens for the first time on the 10th (d) What is the probability that B happens the tenth time on the 6oth (e) What is the expected number of selections until E happens for the the random variable used. selection? selection? tenth time? Name the random variable used.
0 0
Add a comment Improve this question Transcribed image text
Answer #1

a) here as probability of a white ball =8/12=2/3

therefore from binomial distribution P(X<=2)=P(X=0)+P(X=1)+P(X=2)

=5C0(2/3)0(1/3)5+5C1(2/3)1(1/3)4+5C2(2/3)2(1/3)3=0.209877

b)

this follows geometric distribution with parameter p=0.209877

expected selections =1/p=1/0.209877=4.76

c)

P(first time on 10th selection)=P(not happened for first 9 time and happens on 10th time)=(1-0.209877)9*(0.209877)

=0.025189

d)

Probability=P(E happens exactly 9 times in first 59 selection and happens on 60th selection)

=59C9(0.209877)9*(1-0.209877)=0.01598

e)

this follows negative binomial with paramter n=10 and p=0.209877

expected number =r/p=10/0.209877=47.64696

Add a comment
Know the answer?
Add Answer to:
7. An urn contains four black and eight white balls. A sample of five balls is...
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for? Ask your own homework help question. Our experts will answer your question WITHIN MINUTES for Free.
Similar Homework Help Questions
ADVERTISEMENT
Free Homework Help App
Download From Google Play
Scan Your Homework
to Get Instant Free Answers
Need Online Homework Help?
Ask a Question
Get Answers For Free
Most questions answered within 3 hours.
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT