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# I have 7 black and 3 white marbles. I will randomly pick 2 of them. What is the probability that both of them are white? How to solve this?

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I have 7 black and 3 white marbles. I will randomly pick 2 of them. What is the probability that both of them are white? How to solve this?

Guest Feb 23, 2017

#2
+18369
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I have 7 black and 3 white marbles. I will randomly pick 2 of them.

What is the probability that both of them are white?

How to solve this?

$$\begin{array}{|rcll|} \hline && \frac{3}{10} \cdot \frac{2}{9} \\ &=& \frac{1}{15} \qquad (6.\bar{6}\ \%) \\ \hline \end{array}$$

heureka  Feb 24, 2017
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Our math teacher taught us to do 7:3 this is the ratio of black marbles to white marbles. now set it up as a fraction, 7/3. Then since you picked two marbles you will add 7 and 3 because that is your total amount of marbles. So cross multiply 7/3 and 10/2 and simplify if needed, then you have your answer to the probability.

Guest Feb 23, 2017
#2
+18369
+20

I have 7 black and 3 white marbles. I will randomly pick 2 of them.

What is the probability that both of them are white?

How to solve this?

$$\begin{array}{|rcll|} \hline && \frac{3}{10} \cdot \frac{2}{9} \\ &=& \frac{1}{15} \qquad (6.\bar{6}\ \%) \\ \hline \end{array}$$

heureka  Feb 24, 2017

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