16Hit1600
Problem-Solving and Data AnalysisEasySimple probability

Problem-Solving and Data Analysis practice question

A bag contains 3 red marbles and 5 blue marbles. If one marble is chosen at random, what is the probability that it is red?

  1. A. 3/8Correct
  2. B. 3/5
  3. C. 5/8
  4. D. 1/3

Answer: A. 3/8

Probability is favourable outcomes over total outcomes. There are 3 red marbles out of 3 + 5 = 8 marbles in all, so the probability is 3/8.

Why the other answers are wrong

B. 3/5
3/5 compares red with blue. The denominator must be ALL the marbles, 3 + 5 = 8.
C. 5/8
5/8 is the probability of choosing a BLUE marble. The question asks for red.
D. 1/3
1/3 comes from putting the 3 red marbles in the denominator. The denominator is the total number of marbles, 8.

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