Please help me with this probability question...

Alpha6

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Oct 21, 2013
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I can't for the life of me figure out how to solve this...

I have a sack of apples, in which 90% are red and the other 10% are green. If I choose 4 at random, what is the probability that two or less will be red?


I know for the first pick it is a probability of .9 right? I'm not sure how to proceed from there. Any help please?

Thanks.
 
I can't for the life of me figure out how to solve this...

I have a sack of apples, in which 90% are red and the other 10% are green. If I choose 4 at random, what is the probability that two or less will be red?


I know for the first pick it is a probability of .9 right? I'm not sure how to proceed from there. Any help please?

Thanks.
The problem as stated is insoluble. How many apples are in the sack to begin with? Is it sampling with or without replacement? What is the exact statement of the problem?
 
I can't for the life of me figure out how to solve this...

I have a sack of apples, in which 90% are red and the other 10% are green. If I choose 4 at random, what is the probability that two or less will be red?


I know for the first pick it is a probability of .9 right? I'm not sure how to proceed from there. Any help please?

Thanks.
Have you been studying the Binomial Distribution? Can we assume that the sack is large enough that removing 4 will be only small perturbation on the "universal" probability, p=0.90? Then you can use n=4, and the probability of choosing m red is

\(\displaystyle \displaystyle P(m) = p^n\ (1-p)^{n-m}\ \binom n m\)

\(\displaystyle P(\le 2) = P(0) + P(1) + P(2)\)

If you HAVEN'T learned the binomial distribution, you will have to work it out from scratch. Please show us your work so we can see where you get stuck.
 
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