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Question: Answered & Verified by Expert
A bag contains 4 white and 6 black balls. Three balls are drawn at random from the bag. Let X be the number of white balls, among the drawn balls. If σ2 is the variance of X, then 100σ2 is equal to
MathematicsProbabilityJEE MainJEE Main 2022 (28 Jul Shift 2)
Solution:
2842 Upvotes Verified Answer
The correct answer is: 56

Given,

X= Number of white ball drawn,

And bag contains 4 white and 6 black balls, total 3 balls are to be drawn,

So, PX=0=C36C310=16

PX=1=C26×C14C310=12

PX=2=C16×C24C310=310

and PX=3=C06×C34C310=130

X 0 1 2 3
PX 16 12 310 130

So, variance =σ2=PiXi2-PiXi2

σ2=12+1210+310-12+610+1102

σ2=56100

100σ2=56

 

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