Question

An economist wants to estimate the mean per capita income (in thousands of dollars) for a major city in Texas. He believes that the mean income is $24.6, and the standard deviation is known to be $7.9. How large of a sample would be required in order to estimate the mean per capita income at the 80% level of confidence with an error of at most $0.56? Round your answer up to the next integer.

Answer 1

327

Explanation:

Calculation for How large of a sample would be required in order to estimate the mean per capita income

First step is to find z 80% confidence level

At 80% confidence level the z will be:

α/2 = 1 - 80% = 1 - 0.80 = 0.20

α/2= 0.20 / 2 = 0.01

Zα/2= Z0.01= 1.28 from z table

Now let calculate the Sample size using this formula

Sample size = n= [( Zα/2* σ ) / E]^2

Let plug in the formula

n = (1.28*7.9/0.56)^2

n= 326.06

n=327 (Approximately)

Therefore How large of a sample would be required in order to estimate the mean per capita income will be 327