Some white balls put in a basket containing twelve red balls and sixteen black balls. If the probability of picking a white balls from the baskets is 3/7, how many white balls were introduced?

  • A 12
  • B 21
  • C 28
  • D 32
jamb 2004mathematics

The correct answer is B. 21

Let's say the number of white balls introduced is x.

The total number of balls in the basket is 12 + 16 + x = 28 + x. The probability of picking a white ball from the basket is 3/7, so we can write the equation: x / (28 + x) = 3/7.

Solving for x, we get:

7x = 3(28 + x)

7x = 84 + 3x

4x = 84.

Dividing both sides by 4, we get:

x = 21.

So, 21 white balls were introduced into the basket.

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