If the mean and variance of eight numbers 3, 7, 9, 12, 13, 20, x and y be 10 and 25 respectively, then x ∙y is equal to …

Question

Accepted Answer

Correct answer: 54. (54) Mean =x= 3+7+9+12+13+20+x+y8=10 ⇒x+y=16 … (i) Variance ^2= (x_i )^28- (x )^2=25 9+49+81+144+169+400+x^2+y^28-100=25 ⇒x^2+y^2=148 … (ii) (x+y)^2= (16 )^2 ⇒x^2+y^2+2 xy=256 ⇒ xy=54

$If the mean and variance of eight numbers 3, 7, 9, 12, 13, 20, x and y be 10 and 25 respectively, then x ∙ y is equal to \dots$

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