A bag contains 6 red balls and 3 blue balls. 4 balls are selected at random. find the probability of selecting 4 red balls.
Mathematics · High School · Mon Jan 18 2021
Answered on
Given :
Number of red balls = 6
Number of blue balls = 3
Total balls = 3 + 6
= 9
we have to find the probability of selecting 4 red balls out of 10. So,
Formula :
Total number of elementary events = nCr
= 9C4
Here, n = 9
r = 4
Number of favorable events = 6C4
Probability = favorable events/Total events
= 6C4/9C4
= (6!/4! × 2!) × (4! × 5!/9!)
= 5 × 3 × 1/126
= 5/42
So, probability of selecting 4 red balls is 5/42.