View Full Version : probability

deevicsm

04-02-2006, 08:37 PM

Here is the homework question - Jar containing 3red 7 green 4 blue 11 yellow marbles 25 total.

You randomly draw 2 marbles what is the probability of neither being yellow? I said .56% or 14/25 (or should it be 14/25 X 13/24 = )

soroban

04-02-2006, 09:48 PM

Hello, deevicsm!

Jar containing 3 red, 7 green, 4 blue, 11 yellow marbles ... 25 total.

You randomly draw 2 marbles.

What is the probability of neither being yellow?

Your first answer is the probability of getting a non-yellow in one draw.

Your second answer is correct.

The prob. of a non-yellow on the 1<sup>st</sup> draw: \,\frac{14}{25}

The prob. of a non-yellow on the 2<sup>nd</sup> draw: \,\frac{13}{24}

Therefore: \,P(\text{two non-yellows})\;=\;\frac{14}{25}\,\time\frac{13}{24}\;= \;\frac{91}{300}\;\approx\;30\%

deevicsm

04-02-2006, 11:08 PM

Thanks, the more I thought about it the more it made since it was that way.

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