Question

4) On a standard IQ test, *σ* = 15. How many random IQ
scores must be obtained if we want to find the true population
mean, with an allowable error of 0.5 and we want 99% confidence in
the results?

5) Given *n* = 25, *s* = 15, and α = 0.01, find
the maximum error of estimate, *E*.

Answer #1

4)

Given that,

Population standard deviation = = 15

Margin of error = E = 0.5

Z_{/2}
= 2.576

sample size = n = [Z_{/2}*
/ E] ^{2}

n = [2.576 * 15 / 0.5]^{2}

n = 5973

Sample size = n = 5973

5)

t_{
/2,df} = 2.797

Margin of error = E = t_{/2,df}
* (s /n)

= 2.797 * (15 / 25)

Margin of error = E = **8.391**

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