Essay SIT191 – Introduction to Statistics and Data Analysis – Normal Model – Statistics Assignment Help

Assignment Task

 

Question 1 Heights for 8 year old girls are normally distributed with a mean of 127 cm and a standard deviation of 3 cm.

a) Sketch the normal model for the girls’ heights.

b) In what interval would you expect the central 95% of heights to lie?

c) What percentage of the girls are taller than 131 cm?

d) Below what height are the shortest 25% of girls?

e) If 15 girls are randomly selected, find the probability that their average height is greater than 129 cm.

Question 2 A survey on the drinking habits of adults asked the participants how many days a week they consumed alcohol, as well as the type and quantity of alcohol consumed. Of the 1516 adults surveyed, 985 said they consumed alcohol at least twice a week. a) Identify the 5 W’s for this study, if possible. b) Is this an observational study or an experiment? Explain. c) What potential sources of bias could exist in the results? Explain briefly. d) Name and briefly describe a random, as well as a non-random, sampling method for surveying adults. e) From the survey results, create a 95% confidence interval for the true proportion of adults who consume alcohol at least twice a week, and interpret the interval.