Question 1035345: The probability of drawing a black marble from a bag is 1/4, and the probability of drawing a white marble from the same bag is 1/2. What is the probability of drawing a white marble, replacing it, and then drawing a black marble?
Answer by jim_thompson5910(35256)   (Show Source):
You can put this solution on YOUR website! W = event where white marble is drawn
B = event where black marble is drawn
The two events W and B are independent. This is because the marble taken out on the first draw is put back into the bag. Since W and B are independent, we can use this rule
P(W and B) = P(w)*P(B)
Use the rule to get
P(W and B) = P(W)*P(B)
P(W and B) = (1/2)*(1/4)
P(W and B) = (1*1)/(2*4)
P(W and B) = 1/8
1/8 is equivalent to 0.125. Use long division or a calculator
0.125 = 12.5%
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Question:
What is the probability of drawing a white marble, replacing it, and then drawing a black marble?
Answer as a fraction: 1/8
Answer as a decimal: 0.125
Answer as a percentage: 12.5%
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