# Thread: need help with probabibility

1. ## need help with probabibility

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!!

2. 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 $\displaystyle \sum_{k=3}^{10} \frac{n!}{k!(n - k)!}p^k(1 - p)^{n - k}$.