|
A box contains some black balls and 30 white balls. If the probability of drawing a black ball is two fifths of a white ball, then the number of black balls in the box is |
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|
(a) |
6 |
(b) |
12 |
(c) |
18 |
(d) |
30 |
|
A box contains some black balls and 30 white balls. If the probability of drawing a black ball is two fifths of a white ball, then the number of black balls in the box is |
|||||||
|
(a) |
6 |
(b) |
12 |
(c) |
18 |
(d) |
30 |