# s2Watch

This discussion is closed.
#1
the standard deviation of a random variable F is 12.0 the mean of n independent observations of F is denoted F bar

given that the standard deviation of F bar is 1.50 find the value of n

is this a misprint? because whenever i try and calculate it i get silly answers
0
14 years ago
#2
Standard formula: Var(sample mean) = sigma^2/n

Var(Fbar) = 12^2/n
SD(Fbar) = sqrt[Var(Fbar)] = 12/sqrt(n)

12/sqrt(n) = 1.5
sqrt(n) = 8
n = 64
0
#3
(Original post by Jonny W)
Standard formula: Var(sample mean) = sigma^2/n

Var(Fbar) = 12^2/n
SD(Fbar) = sqrt[Var(Fbar)] = 12/sqrt(n)

12/sqrt(n) = 1.5
sqrt(n) = 8
n = 64
i see where i went wrong! thanks a lot
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