A bag contains 4 white , 5 red and 6 blue balls. Three balls are drawn at rand dom from the bag .The probability that all of them are red.is :
Created: 4 years ago |
Updated: 2 weeks ago
best ans
Let S be the sample space
Then, n(S) = number of ways of drawing 3 balls out of 15
= 15C3 = (15 × 14 × 13)/(3 × 2 × 1) = 455
Let E = event of getting all the 3 red balls
∴n(E) = 5C3 = 5C2 = (5 × 4)/(2 × 1) = 10
∴P(E) = n(E)/n(S) = 10/455 = 291
Then, n(S) = number of ways of drawing 3 balls out of 15
= 15C3 = (15 × 14 × 13)/(3 × 2 × 1) = 455
Let E = event of getting all the 3 red balls
∴n(E) = 5C3 = 5C2 = (5 × 4)/(2 × 1) = 10
∴P(E) = n(E)/n(S) = 10/455 = 291
Md Azizur Rahman
Founder of Satt
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