Question

A market research company 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 0.08. A consultant has informed them that a previous study found the mean to be 7.3 energy drinks per week and found the standard deviation to be 0.7. What is the minimum sample size required to create the specified confidence interval

Answer 1

Answer: 126 samples

Step-by-step explanation:

Given that :

Standard deviation (σ) = 0.7

Mean (m) = 7.3

Error (E) = 0.08

α = 80%

The sample size n can be obtained using the relation :

n = [(Zcrit * standard deviation) / Error]^2

The Zcritical at 80% = 1.282

Hence,

n = ((1.282 * 0.7) / 0.08)^2

n = (0.8974 / 0.08)^2

n = 11.2175^2

n = 125.83230625

n = 126