# Basic Statistics Problem

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• Oct 17th 2010, 10:58 AM
Futant
Basic Statistics Problem
I was sick for the first half of first semester, and I'm doing a two-week intensive catch-up on an introduction to probability and statistics course. However, the textbook is very vague and jumps from very simple probabilities (tree diagrams for simple events) to this question, that I think I know how to compute, but don't know how to write properly in terms of "showing my work."

Rolling 10 six-sided die, what is the probability that exactly 4 will roll a six?

My gut stays that the probability would be [(1/6)^4]x[(5/6)^6], though that doesn't compensate for possible orders.

Where should I start? What are resources online that are likely better than this subpar textbook?

Thank you in advance!

Futant.
• Oct 17th 2010, 11:09 AM
CaptainBlack
Quote:

Originally Posted by Futant
I was sick for the first half of first semester, and I'm doing a two-week intensive catch-up on an introduction to probability and statistics course. However, the textbook is very vague and jumps from very simple probabilities (tree diagrams for simple events) to this question, that I think I know how to compute, but don't know how to write properly in terms of "showing my work."

Rolling 10 six-sided die, what is the probability that exactly 4 will roll a six?

My gut stays that the probability would be [(1/6)^4]x[(5/6)^6], though that doesn't compensate for possible orders.

Where should I start? What are resources online that are likely better than this subpar textbook?

Thank you in advance!

Futant.

Have you covered the binomial distribution?

CB
• Oct 17th 2010, 12:25 PM
Futant
No, we have not. Looking at my text book, that is covered in the next chapter. Should I just do the next chapter first, and come back and look at this problem again?

Thanks!

Futant.
• Oct 17th 2010, 08:01 PM
CaptainBlack
Quote:

Originally Posted by Futant
No, we have not. Looking at my text book, that is covered in the next chapter. Should I just do the next chapter first, and come back and look at this problem again?

Thanks!

Futant.

Number the dice, than the probability P0 that a particular 4 will show a 6 and none of the others is what you posted in your first post.

The probability you seek is P0 times the number of ways that the four dice to show a 6 can be selected from the 10.

CB