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# A2 Statistics Help watch

1. I need some help for this Sampling question please.

A random sample of 2n observations is taken of the random variable X~B(n,p) and p>0.5. The sample mean is denoted by Xbar. It is given that Var (Xbar) = 0.08 and E(Xbar) = 64.

a) Find the values of p and n.

I have used np = 64 and npq/2n = 0.08. My answers are n= 76 and p = 0.84. However, the textbook answers are n = 80 and p = 0.8.
2. (Original post by VTan)
I need some help for this Sampling question please.

A random sample of 2n observations is taken of the random variable X~B(n,p) and p>0.5. The sample mean is denoted by Xbar. It is given that Var (Xbar) = 0.08 and E(Xbar) = 64.

a) Find the values of p and n.

I have used np = 64 and npq/2n = 0.08. My answers are n= 76 and p = 0.84. However, the textbook answers are n = 80 and p = 0.8.
you can make two equations;

sub the info from first line and third line into (2) and solve for n (quadratic), only one value is valid due to restrictions on p

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