You want to estimate the mean number of sentences in a magazineadvertisement. How many magazine advertisements must beincluded in the sample if you want to be 95% confident that thesample mean is within 1 sentence of the population mean ? (sigma =5)
Answer:
96
Step-by-step explanation:
We have level of confidence = 95%
Alpha = 1-0.95
= 0.05
Alpha/2 = 0.025
Z-alpha/2 = 1.96
E = margin of error = 1
For this question the formula to derthe sample size is given as:
n = [(Za/2 x sigma)/E]²
n = (1.96 x 5/1)²
n = 9.8²
= 96.04
So 96 magazines advertisement must be included in the sample to be 95% confident.
