Question

a market surveyor wishes to know how many energy drinks teenagers drink each week.they want to construct a 80% confidence interval with an error of no more than 0.07. a consultant had informed them that a previous study found the mean to be 3.6 energy drinks per week and found the variance to be 1.44.what is the minimum sample size required to create the specified confidence interval

Answer 1

Confidence level = 0.80

Zc = 1.28 ( Using z table)

Margin of error = E = 0.07

Variance = 1.44

Standard deviation is square root of the variance.

Population standard deviation = = 1.2

We have to find sample size (n)