# Thread: Probability Problem!

1. ## Probability Problem!

Please help! I really have no idea where to start with this problem.

A geological study indicates that an exploratory oil well should strike oil with probability of .4. What is the probability that the 5th strike comes on the 8th well drilled? Give your answer as a fraction reduced to lowest terms.

2. Originally Posted by sweeetcaroline
Please help! I really have no idea where to start with this problem.

A geological study indicates that an exploratory oil well should strike oil with probability of .4. What is the probability that the 5th strike comes on the 8th well drilled? Give your answer as a fraction reduced to lowest terms.
This is a negative binomial distribution question. Read this: Negative binomial distribution - Wikipedia, the free encyclopedia