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Statistics question

2023 · 31 Jan · Shift 2 · Q28
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Statistics question

2023 · 31 Jan · Shift 2 · Q28

JEE MainMathematicsStatisticsMCQ+4 / −1
Let the mean and standard deviation of marks of class A of 100 students be respectively 40 and α(>\alpha(\gtα(> 0 ), and the mean and standard deviation of marks of class BBB of nnn students be respectively 55 and 30 −α-\alpha−α. If the mean and variance of the marks of the combined class of 100+n100+\mathrm{n}100+n studants are respectively 50 and 350 , then the sum of variances of classes AAA and BBB is :
  1. A
    450
  2. B
    900
  3. C
    650
  4. D
    500
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