Answering Exams

A bag contains five white and four red balls. Two balls are picked at random from the bag. What is the probability that they both are different color?

A bag contains five white and four red balls. Two balls are picked at random from the bag. What is the probability that they both are different color?

A. 4/9
B. 5/9 (Correct)
C. 7/9
D. 8/9

Explanation:

Two balls can be picked from nine balls in ⁹C₂ ways.

We select one white ball and one red ball from five white balls and four red balls. This can be done ⁵C₁ . ⁴C₁ ways.
The required probability = (5 * 4)/⁹C₂ = 20/36 = 5/9

 

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