please help me I've waited for hours

The average price of a gallon of unleaded regular gasoline was reported to be $2.34 in northern Kentucky (The Cincinnati Enquirer, January 21, 2006). Use this price as the population mean, and assume the population standard deviation is $.20.

1) Calculate the sample size necessary to guarantee at least .95 probability that the sample mean is within $.03 of the population mean

2 answers

Formula:

n = [(z-value * sd)/E]^2

z-value = 1.96
sd = .20
E = .03

Plug the values into the formula and finish the calculation. Round your answer to the next highest whole number.
170