The file Market Penetration contains Facebook penetration values (the percentage of a country's population that are Facebook users) for 15 countries:
50.19 25.45 4.25 18.04 31.66 49.14 39.99 28.
29 37.52 28.87 37.73 46. 04 52.24 38.06 34.91
Source: Data extracted from www.socialbakers.com/facebookstatistics/.
a. Construct a 95% confidence interval estimate for the population mean Facebook penetration.
b. What assumption do you need to make about the population to construct the interval in (a)?
c. Given the data presented, do you think the assumption needed in (a) is valid? Explain.