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MATH PROBLEM HELP!!!?
In San Francisco, 30% of workers take public transportation daily (USA Today, December 21,2005).
In a sample of 10 workers, what is the probability that exactly three workers take public transportation daily (to 4 decimals)?
In a sample of 10 workers, what is the probability that at least three workers take public transportation daily (to 4 decimals)?
2 Answers
- 10 years agoFavorite Answer
This is a Binomial Distribution problem.
First, the outcomes can be classified as success(workers take public transportation) and failure(workers do not take public transportation).
Next, we are given that Pr(success) = .3 while Pr(failure) = .7
1) We have 10 trials. Thus, Pr(exactly 3 workers take public transportation daily)
= 10C3 * .3^3 * .7^7 = 120 * .027 * .0823543 = .2668
2) Again, we have 10 trials. Pr(at least 3 workers take public transportation daily)
= 1 - Pr(less than 3 workers take public transportation daily) (*They are complements*)
= 1 - Pr(2 take) - Pr(1 takes) - Pr(0 take) = 1 - .2335 -.1211 - .0282 = .6172.
- 5 years ago
Nine percent of undergraduate students carry credit card balances greater than $7000
(Reader’s Digest, July 2002). Suppose 10 undergraduate students are selected randomly to
be interviewed about credit card usage.
a. Is the selection of 10 students a binomial experiment? Explain.
b. What is the probability that two of the students will have a credit card balance greater
than $7000?
c. What is the probability that none will have a credit card balance greater than $7000?
d. What is the probability that at least three will have a credit card balance greater than $7000?
