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AMO 2021 - Secondary 2 (Grade 8) Question 8

AMO · AMO 2021 - Secondary 2 (Grade 8)

Question 8

In a dark room, box A contains four green and six red balls; box B contains eight green and two red balls. Amy randomly picks a box and then a ball. The ball is green. What is the probability it came from box A? Clarification: the two boxes are equally likely to be selected, and each ball in the chosen box is equally likely.

Question illustration
  1. $\frac12$
  2. $\frac13$
  3. $\frac14$
  4. $\frac15$
  5. $\frac16$