Exam 1

The following table gives the results of a study examining smartphone ownership by U.S. adults.

Smartphone Use Among U.S. Adult Women and Men Men Women Total

Own a smartphone 1238 650 1888 Does not own a smartphone 542 362 904

Total 1780 1012 2792

a. What percent of all respondents own smartphones? Calculate the percent, then round to 2 decimal places. Show your work!

b. What percent of men own smartphones? Calculate the percent, then round to 2 decimal places. Show your work!

c. What percent of smartphone owners are men? Calculate the percent, then round to 2 decimal places. Show your work!

d. What percent of women own smartphones? Calculate the percent, then round to 2 decimal places. Show your work!

e. Which group are more likely to be own smartphones, men or women? Explain your reasoning.

The table below shows the estimated value for a sample of 2010 Honda Accord LX sedans for various miles driven. Use the table to answer the questions that follow.

Odometer Reading (miles)

OR

Estimated value from NADA (dollars)

EV 40,000 7275 50,000 7275 60,000 6825 70,000 6300 80,000 5850 90,000 5425 100,000 5050 120,000 4450

a. Which variable is the explanatory variable and which is the response variable?

Explanatory: _________________________ Response: _____________________________

b. Enter the data into StatKey or your calculator. Plot the data and view the regression line

c. Does the association between the variables appear positive or negative? Strong or weak?

______________________________________________

d. Find the correlation r and list it here, rounding to 3 decimal places:___________________

e. Use StatKey to find the regression equation, rounding to 3 places after the decimal. Use the variable names OR for Odometer Reading and EV for Estimated value.

____________________________________________________________________________

f. Use your equation to estimate the value of a 2010 Honda Accord LX with 150,000 miles on the odometer. Round your answer to one decimal place and write your answer in a sentence.

______________________________________________________________________________

______________________________________________________________________________

______________________________________________________________________________

Here is a dot plot of the male math SAT scores from the student survey data. The scores have been converted to z-scores; the original data had a mean of 616 and a standard deviation of 74. The data appears to approximately fit a bell-shaped curve.

Len’s math SAT score is 695 and he feels pleased with himself.

a. Convert Len’s math SAT score to a z-score.

b. Place Len’s z-score on the graph above. Is Len’s z-score within one standard deviation of the mean? Within 2 standard deviations of the mean? Indicate how you reached your conclusion by referring to the graph.

c. (2 pts)The college board originally told Len that he did better than 86% of students who took the test. One year later Len took the SAT again, and he earned the same score of 695. This time, however, the College Board told Len that he did better than 83% of students who took the test. How could that be?

1. reasoning:
2. showWork1:
3. showWork2:
4. Explanatory:
5. Response:
6. sentence1:
7. sentence2:
8. sentence3:
9. z:
10. showWork3:
11. showWork4:
12. association:
13. correlation:
14. regression:
15. conclusion:
16. students: