Algebraic ball counts after additions

Algebraic ball counts after additions

Secondary 2
2 marks
TGM Original Questions

Core stretch

A bag contains \(n\) white balls and \(2n\) black balls. One ball is selected at random.

  1. Write the probability of drawing white.[1]
  2. Five white and seven black balls are added. The probability of black is now \(\frac{5}{8}\). Find the initial number of black balls.[1]

Solution:

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Answer:(a) \(\frac{1}{3}\) (b) \(8\) black balls.

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