N = 8(adsbygoogle = window.adsbygoogle || []).push({});

Mean = 2.10

stDev = 0.537

What size sample is required to construct a 95% confidence interval with a margin of error of 0.3?

try n = 12, t(.975) with 11 deg. of freedom = 2.2001

so n = ( (.537* 2.2001) / (.3))^2 = 15.5

try n = 14, i get n = 14.95

n = 15, n = 14.74

Why is this a trial and error?

What I don't get is what are we trying to get n to equal?

the answer: n must be between 14 and 15 so, use n = 15.

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# Size sample required to construct a 95% C.I. with margin of error

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