If there are 30 red and blue marbles in a jar, and the ratio of red to

Question

If there are 30 red and blue marbles in a jar, and the ratio of red to blue marbles is 2:3, what is the probability that, drawing twice, you will select two red marbles if you return the marbles after each draw?

A. 22/145
B. 1/25
C. 2/25
D. 3/25
E. 21/25

A. 1/25
B. 2/25
C. 3/25
D. 4/25
E. 21/25

XSatishX · Answer

We don't need the total number of marbles here as we have the ratio of red to blue marbles in the jar.
So the probability of picking a red marble = 2/5
As per the question, we are returning the marbles so every time we pick a marble the bag will have 30 marbles in the same ratio.

So the probability of picking two red marbles = 2/5*2/5 = 4/25
Not sure why this answer choice is missing here. If we are not returning these marbles than the probability will be 12/30*11/29 = 22/145.

stne · Answer

Ratio of Red to Blue = 2:3 We have total 30
Hence  5x=30, x= 6 
Since we have 12 red marbles 
Probability of picking 2 red marbles 
 \frac{12}{30}*\frac{12}{30} =  \frac{144}{900} = \frac{4}{25}

Bunuel  please look into this. 
Ans should be  \frac{4}{25}

MathRevolution · Answer

R + B = 30

The ratio of R: B is 2: 3. Therefore, R =  \frac{2 }{ 5}  * 30 = 12 and B = 30 - 12 = 18

P(R) =  \frac{12 }{30}  =  \frac{2 }{ 5}  and P(B) =  \frac{3 }{ 5}

Drawing red twice without replacement:  \frac{2 }{ 5}  *  \frac{2 }{ 5}  =  \frac{4 }{ 5}

Answer D

ruis · Answer

But the question asks drawing red twice WITH replacement. 
Without replacement it would be = 2/5 + 11/29 right?

If there are 30 red and blue marbles in a jar, and the ratio of red to

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If there are 30 red and blue marbles in a jar, and the ratio of red to

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