ACTIVITY H: Sampling Theory and Estimation of Parameters

1. A random sample of 50 students in Holy Angel University shows that they spend an average of 3 hours per day on social media apps with a standard deviation of 0.5 hours. Assume a normal distribution. Construct a $90\mathrm{\%}$ and $97\mathrm{\%}$ confidence interval for the average number of hours spent on social media apps per day.

2. A study was conducted in which two types of fried chicken, Jollibee and KFC, were compared. Number of fried chickens sold, was measured. 90 Jollibee branches were surveyed while 80 were surveyed for KFC. The average fried chicken sold was 7,020 for Jollibee and 8,100 fried chickens for KFC. Find a $94\mathrm{\%}$ and $98\mathrm{\%}$ confidence interval on .Assume that the population standard deviations are 1000 and 500 for KFC and ????--?????????Jollibee, respectively.

3. The following are the average lengths of today’s top 10 Global Spotify hits, in minutes. 3.02, 2.85, 3.33, 3.43, 2.9, 2.93, 3.23, 2.77, 2.45, and 2.88. Find a $95\mathrm{\%}$ confidence interval for the variance of the lengths of this generation’s music, assuming a normal population.