stats 2

This is a 2-hour timed closed book exam. You can use a calculator (not your phone) for calculations.

Questions:

1. Facebook remains the top choice of social media over all ages, with 65% using Facebook most often among those using social media sites. However, more visually oriented social networks such as Snapchat and Instagram continue to draw in younger audiences. When asked “Which one social networking site or service do you use most often?’’ here are the top sites chosen by Americans aged 12–24 who currently use any social networking site or service:

Social Media Site Percentage Who Use Most Often

Facebook 43%

Instagram 18%

Snapchat 15%

Twitter 8%

Google+ 4%

Pinterest 3%

a)  What is the sum of the percentages for these top social media sites? What percent of Americans aged 12–24 use other social media sites most often?

b)  Make a bar graph to display these data. Be sure to include an “Other social media site’’ category.

c)  Would it be correct to display these data in a pie chart? Why or why not?

2. Table below gives the number of active nurses per 100,000 people in each state.

a) Why is the number of nurses per 100,000 people a better measure of the availability of nurses than a simple count of the number of nurses in a state?

b) Make a stemplot that displays the distribution of nurses per 100,000 people. The data will first need to be rounded. What units are you going to use for the stems? The leaves? You should round the data to the units you are planning to use for the leaves before drawing the stemplot. Write a brief description of the distribution. Are there any outliers? If so, can you explain them?

Active Nurses per 100,000 people, by state

State Nurses	State Nurses	State Nurses2
Alabama. 911	Louisiana. 881	Ohio. 1021
Alaska. 717	Maine 1093	Oklahoma 742
Arizona 585	Maryland 906	Oregon 803
Arkansas 798	Massachusetts 1260	Pennsylvania 1030
California 630	Michigan 849	Rhode Island 1104
Colorado 831	Minnesota 1093	South Carolina 834
Connecticut 1017	Mississippi 950	South Dakota 1296
Delaware 1155	Missouri 1038	Tennessee 984
Florida 814	Montana 855	Texas 678
Georgia 665	Nebraska 1054	Utah 635
Hawaii 689	Nevada 609	Vermont 914
Idaho 682	New Hampshire 1006	Virginia 764
Illinois 901	New Jersey 858	Washington 814
Indiana 901	New Mexico 614	West Virginia 953
Iowa 1022	New York 848	Wisconsin. 946
Kansas 934	North Carolina 940	Wyoming 864
Kentucky 1003	North Dakota 968	District of Columbia 1483

3. Most mobile usage occurs via apps, particularly on smartphones, with time on smartphone apps now surpassing time spent on desktops in the United States. Digital media can be accessed on mobile platforms by using apps on a smartphone or tablet or by using a browser on a smartphone or tablet, or it can be accessed on the more traditional desktop platform (including laptops). Here is the breakdown of the share of digital media time by access method in the United States, Canada, and the United Kingdom:

a)  Draw a bar graph for the distribution of the method for Canada. Do the same for the United States and United Kingdom, using the same scale for the percent axis.

b)  Describe the most important difference in the distributions of the share of digital time by access method for the three countries. How does this difference show up in the bar graphs?

c)  Explain why it is appropriate to use a pie chart to display any of these distributions. Draw a pie chart for each distribution. Do you think it is easier to compare the three distributions with bar graphs or pie charts? Explain your reasoning.

4. The final grades of 80 mathematics students are recorded in the following table:

68	73	61	66	96	79	65	86
84	79	65	78	78	62	80	67
75	88	75	82	89	67	73	73
82	73	87	75	61	97	57	81
68	60	74	94	75	78	88	72
90	93	62	77	95	85	78	63
62	71	95	69	60	76	62	76
88	59	78	74	79	65	76	75
76	85	63	68	83	71	53	85
93	75	72	60	71	75	74	77

a) Create a Histogram and describe it.

b) Find the lowest grade.

c) Find the highest grade.

d) Find the sample mean or average.

e) Find the median.

f) Calculate the standard deviation.

g) Show the Five Number Summary

5. From the data below, find the correlation between height and weight in individuals. Show the corresponding chart.

S.No	Height (cm)	Weight (Kg)
1	110	44
2	116	31
3	124	43
4	129	45
5	131	56
6	138	79
7	142	57
8	150	56
9	153	58
10	155	92
11	156	78
12	159	64
13	164	88
14	168	112
15	174	101