Question

What is the minimum sample size required for estimating μ for N(μ, σ²=121) to within ± 2 with confidence levels 95%, 90%, and 80%?

a. Find the minimum sample size for the 95% confidence level. Enter an integer below. You must round up.

b. Find the minimum sample size for the 90% confidence level.

c. Find the minimum sample size for the 80% confidence level.

Answer 1

a)

for 95 % CI value of z=	1.960
standard deviation σ=	11.00
margin of error E =	2
required sample size n=(zσ/E)2                                         =	117.0

b)

for 90 % CI value of z=	1.645
standard deviation σ=	11.00
margin of error E =	2
required sample size n=(zσ/E)2                                         =	82.0

c)

for 80 % CI value of z=	1.282
standard deviation σ=	11.00
margin of error E =	2
required sample size n=(zσ/E)2                                         =	50.0