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From a lot of 12 items containing 3 defectives, a sample of 5 items is drawn at random. Let the random variable X denote the number of defective items in the sample. Let items in the sample be drawn one by one without replacement. If variance of X is m n , where gcd (m, n)=1 , then n-m is equal to _________

Correct answer

0

Step-by-step solution

aligned & a =1- ^3 C ₅ ¹² C ₅ & ~b =3 ^9 C ₄ ¹² C ₅ & c =3 ^9 C ₃ ¹² C ₅ & ~d =1 ^9 C ₂ ¹² C ₅ & u =0 . a +1 . b+2 c+3 d =1.25 & ^2=0 . a +1 . b+4 . c+9 ~d - u ^2 & ^2= 105 176 aligned Ans. 176-105=71

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