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Recent questions tagged variance

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2
Random Variable
Let X and Y are two random variables with E(X)=10,E(Y)=20 and Var(X)=25,Var(Y)=36 and E(X.Y)=225. Now consider Z=aX-bY+1. Find a and b when E(Z)=1 and Var(Z)=1.
Let X and Y are two random variables with E(X)=10,E(Y)=20 and Var(X)=25,Var(Y)=36 and E(X.Y)=225.Now consider Z=aX-bY+1.Find a and b when E(Z)=1 and Var(Z)=1.
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5
Variance
There are two data sets,each of size 5. The variances of those sets are 4 and 5; means are 2 and 4 respectively. If the sets are combined, what would be variance of combined data? (A) 10/11 (B) 11/13 (C) 11/2 (D) 13/11
There are two data sets,each of size 5. The variances of those sets are 4 and 5; means are 2 and 4 respectively. If the sets are combined, what would be variance of combi...
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6
Virtual Gate
Let X and Y be two independent random variables. Suppose, we know that Var(√5X − √2Y) = 15 and Var(−√2X + Y) = 6.5. Var(X) and Var(Y) are: (A) Var(X) = 2.5, Var(Y) = 2 (B) Var(X) = 2, Var(Y) = 2.5 (C) Var(X) = 3, Var(Y) = 1.5 (D) Var(X) = 1.5, Var(Y) = 2.5
Let X and Y be two independent random variables. Suppose, we know that Var(√5X − √2Y) = 15 and Var(−√2X + Y) = 6.5. Var(X) and Var(Y) are: (A) Var(X) = 2.5,...
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7
VARIANCE
The mean of 100 observation is 50 and there standard deviation is 5. The sum of all squares of all the observation is 1) 50000 2) 250000 3) 252500 4) 25500
The mean of 100 observation is 50 and there standard deviation is 5. The sum of all squares of all the observation is1) 500002) 2500003) 2525004) 25500
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2 answers
8
Variance
consider the first 10 positive integers . If we multiply each number by -1 and then add 1 to each number , the variance of the numbers so obtained is 1) 6.5 2) 8.25 3) 3.87 4) 2.87
consider the first 10 positive integers . If we multiply each number by -1 and then add 1 to each number , the variance of the numbers so obtained is1) 6.52) 8.253) 3.874...
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9
Variance
Variance of 1st n positive integers is a)(n2-1)/12 b)(n+1)/6 c)(n-1)(2n+1)/3 d)n(n-1)
Variance of 1st n positive integers isa)(n2-1)/12b)(n+1)/6c)(n-1)(2n+1)/3d)n(n-1)
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