Question 1035345
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%