In a bag there are a certain number of black balls and white balls. The probability of picking up exactly 1 white ball when 2 balls are randomly drawn, is 1/2. Which of the following is the ratio of the number of black balls to white balls in the bag  Choose the correct choice from the following options:
A) 1:2	B) 2:1	C) 1:1	D) 4:1	E) 1:4
since the probability of drawing a white ball out of two picks is 1/2.   the ratio of the white ball to black balls should be 1:1   1:1
<result>C</result>
In a bag there are a certain number of black balls and white balls. The probability of picking up exactly 1 white ball when 2 balls are randomly drawn, is 1/2. Which of the following is the ratio of the number of black balls to white balls in the bag