Descriptive Statistics

Instructions: Show your work completely and circle your final answers. I am attaching a formula page (last page) for you. You can use it. You may not talk to any of the students or share any tables, calculators from any other students. In your calculations, use two decimal places of accuracy.

1. (11 points) A market research team compiled the following frequency distribution for families residing in Randolph County. In this table x represents the number of evenings and f represents the number of families dine outside their home during a week. x f

0
30

1
50

2
10

3
10

(i) ( 4 points)Calculate the mean (Expected) number of dines outside their home.
(ii) (5 points) Calculate the variance of the number of dines
(iii) (2 points) Calculate the standard deviation of the number of dines

2. (26 points) The 2000 US census also asked for each person’s age. Suppose that a sample of households taken from the census data showed the age of the first person (spouse) recoded on the census form to be as follows. 42 29 31 38 55 27 28 33 49 69 25 21 38 47 63 22 38 52 50 41 19 22 29 61 52 26 35 38 29 31 48 26 33
(i) (3 points) Compute a stem and leaf display
(ii) (5 points) Develop a frequency distribution using class intervals starting with the first class interval as 10-20 (20 is not included), second class interval as 20-30 (30 is not included) and so on.
(iii) (6 points) What percent of people are less than 40 years old? What percent of