There rotten apples are mixed accidently with seven good apples and four apples are drawn one by one without…

There rotten apples are mixed accidently with seven good apples and four apples are drawn one by one without replacement. Let the random variable X denote the number of rotten apples. If μ and σ2 represent mean and variance of X, respectively, then 10μ2+σ2 is equal to
  1. 20
  2. 250
  3. 25
  4. 30

Solution

There rotten apples are mixed accidently with seven good apples,

And four apples are drawn one by one without replacement.

Now the random variable X denote the number of rotten apples.

And μ and σ2 represent mean and variance of X, respectively, 

So, now plotting the table of given data we get,

x P(x) xP(X) x2P(X)
0 16 0 0
1 12 12 12
2 310 610 1210
3 130 110 930

Now mean is given by, xP(x)=62=μ

And variance is given by σ2=x2P(x)-μ2

So, by putting the value from above table we get,  σ2+μ2=0+12+1210+930=2

Hence, 10σ2+μ2=20

Asked in: JEE Main 2023 (29 Jan Shift 1)

Practice more Probability questions on Aicharya