Hello,(adsbygoogle = window.adsbygoogle || []).push({});

Can someone please tell me whether I can use negative binomial distribution for this question.

"If there are 3 types of books in a bookstore and each book has an equal probability of being bought. What is the expected number of purchases to get all 3 books?"

Using negative negative binomial, i get E(Y)=3/(1/3)=9. Is it just supposed to be this or is there something else to a question like this?

Any help would be great.

Thank you in advance.

**Physics Forums - The Fusion of Science and Community**

Dismiss Notice

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Expected value and negative binomial distribution

Loading...

Similar Threads - Expected value negative | Date |
---|---|

A Value at Risk, Conditional Value at Risk, expected shortfall | Mar 9, 2018 |

I Conditional Expectation Value of Poisson Arrival in Fixed T | Dec 21, 2017 |

B The expectation value of superimposed probability functions | Sep 9, 2017 |

I Expected Value Question | Feb 17, 2017 |

Sample distribution and expected value. | Dec 10, 2015 |

**Physics Forums - The Fusion of Science and Community**