A bag contains 4 white, 5 red and 6 blue balls.
A bag contains 4 white, 5 red and 6 blue balls. Three balls are drawn at random from the bag. The probability that all of them are red, is:
Answer/Solution
2/91
Steps/Work
Let S be the sample space.
Then, n(S) = number of ways of drawing 3 balls out of 15
= 15C3
= (15 x 14 x 13)
(3 x 2 x 1)
= 455.
Let E = event of getting all the 3 red balls.
n(E) = 5C3 = 5C2 = (5 x 4)/(2 x 1)= 10.
P(E) = n(E)/n(S)=10/455=2/91.
Ans:D
Then, n(S) = number of ways of drawing 3 balls out of 15
= 15C3
= (15 x 14 x 13)
(3 x 2 x 1)
= 455.
Let E = event of getting all the 3 red balls.
n(E) = 5C3 = 5C2 = (5 x 4)/(2 x 1)= 10.
P(E) = n(E)/n(S)=10/455=2/91.
Ans:D