Probability with Dice

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October 22nd 2009, 06:42 PM
Sakurazaki

Probability with Dice

A fair die is thrown 14 times. What is the probability of getting point 1 on exactly 2 of the 14 throws?

This one I am not too sure how to go about this.

Would someone try to give me hints or walk me through it?

Thanks.
October 22nd 2009, 08:18 PM
tonio

Quote:

Originally Posted by Sakurazaki

A fair die is thrown 14 times. What is the probability of getting point 1 on exactly 2 of the 14 throws?

This one I am not too sure how to go about this.

Would someone try to give me hints or walk me through it?

Thanks.

Read, or google, about "Bernoulli formula" in "binomial distribution": the probability is given by $\left(\begin{array}{c}14\\2 \end{array}\right) \left(\frac{1}{6}\right)^2 \left(\frac{5}{6}\right)^{12}$

Tonio
October 23rd 2009, 02:52 AM
mr fantastic

Quote:

Originally Posted by Sakurazaki

A fair die is thrown 14 times. What is the probability of getting point 1 on exactly 2 of the 14 throws?

This one I am not too sure how to go about this.

Would someone try to give me hints or walk me through it?

Thanks.

Let X be the random variable number of 1's thrown.

X ~ Binomial(n = 14, p = 1/6)

Calculate Pr(X = 2).
October 23rd 2009, 04:49 AM
Sakurazaki

Ok I got the answer. Thanks for your help.

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