Question

A bag contains 7 red balls, 4 blue balls and 3 yellow balls. 3 balls are drawn at random and not replaced. What is the probability that all three balls are red ?

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Answer 1

7/14 = 1/2

Explanation:

Answer 2

Total number of balls equals 14

Probability of 1 red ball = 7 / 14

Probability of second red ball = 6 / 13

Probability of third red ball = 5 / 12

Total probability = 7 / 14 * 6 / 13 * 5 / 12

Total = 1/2 * 6/13 * 5/12

Common denominator = 312

Total = (1 * 6 * 5) / 312) = 30 / 312 = .096

One can enter fractions into a calculator and get the same result.