A box contains 5 white , 8 red ,9 black ball . two balls picked randomly what is pro they are not black
Answers
Answer:
p(not black) = 13/22
Step-by-step explanation:
I hope so this is ans
Given:
5 white, 8 red, 9 black balls
To find:
The probability of picking two balls that are not black
Solution:
The probability of picking two balls that are not black is 26/77.
We can find the probability by following the given steps-
We know that there are 5 white balls, 8 red balls, and 9 black balls.
So, the total number of balls=number of white balls+number of red balls+number of black balls
=5+8+9
=22
The number of balls that are not black=red balls+white balls=5+8=13 balls
Out of these, we have to pick out 2 balls randomly.
We will use the concept of combinations where nCr=n!/r!(n-r)!
The number of ways of choosing 2 balls that are not black=13C2
=13!/2!×11!
=13×12×11!/2!×11!
=13×12/2
=13×6
=78
Similarly, the total number of ways of choosing two balls=22C2
=22!/2!×20!
=22×21×20!/2!×20!
=22×21/2
=11×21
=231
The probability of picking two balls that are not black=13C2/22C2
=78/231
=26/77
Therefore, the probability of picking two balls that are not black is 26/77.