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JEE Main 202329 JanuaryMorning Shift
Exam
JEE Main
Year
2023
Date
29 January
Shift
Morning Shift
Subject
Mathematics
Chapter
Probability

JEE Main 2023 · 29 January · Morning Shift · Mathematics · Probability

There rotten apples are mixed accidently with seven good apples and...

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 μand\mu and{\sigma}^{2}representmeanandvarianceofX,respectively,thenrepresent mean and variance of X, respectively, then10(μ2+σ2)\left({\mu}^{2} + {\sigma}^{2}\right) is equal to

Options

  1. A2020
  2. B250250
  3. C2525
  4. D3030

Correct answer

A. 2020

Step-by-step 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\mu and σ2{\sigma}^{2} represent mean and variance of X, respectively,

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

xx P(x)P ( x ) xP(X)xP ( X ) x2P(X){x}^{2}P ( X )
00 16\dfrac{1}{6} 00 00
11 12\dfrac{1}{2} 12\dfrac{1}{2} 12\dfrac{1}{2}
22 310\dfrac{3}{10} 610\dfrac{6}{10} 1210\dfrac{12}{10}
33 130\dfrac{1}{30} 110\dfrac{1}{10} 930\dfrac{9}{30}

Now mean is given by, ∑xP(x)=62=μ∑ xP ( x ) = \dfrac{6}{2} = \mu

And variance is given by σ2=∑x2P(x)−μ2{\sigma}^{2} = ∑ {x}^{2}P ( x ) - {\mu}^{2}

So, by putting the value from above table we get, σ2+μ2=0+12+1210+930=2{\sigma}^{2} + {\mu}^{2} = 0 + \dfrac{1}{2} + \dfrac{12}{10} + \dfrac{9}{30} = 2

Hence, 10(σ2+μ2)=2010\left({\sigma}^{2} + {\mu}^{2}\right) = 20

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