ok so the question is 30% of workers take public transportation. In a sample of 10 workers what is the probability that at least three will take public transportation daily.

Thanks!!

Results 1 to 2 of 2

- Feb 18th 2010, 05:31 PM #1

- Joined
- Feb 2010
- Posts
- 19

- Feb 18th 2010, 06:26 PM #2

- Joined
- Dec 2009
- Posts
- 226

The setting appears to be binomial. Therefore, sum the binomial probability theorem $\displaystyle \frac{n!}{k!(n - k)!}p^k(1 - p)^{n - k}$ (where n is the number of trials, k is the number of successes, and p is the probability of success) for k = 3, k = 4, ..., k = 9, and k = 10, or $\displaystyle \sum_{k=3}^{10} \frac{n!}{k!(n - k)!}p^k(1 - p)^{n - k}$.