Name: ______CHS Statistics Chapter 9 Test Study Guide #2

1.)Determine the type of association for each pair of variables (positive, negative or none).

  1. ______Scuba Diving: depth of dive and visibility
  1. ______Drivers: blood alcohol level and reaction time.
  1. ______Students: Shoe size and grade point average
  1. ______Lightning strikes: distance from the lightning and time delay of the thunder

2.)Rank the bivariate data set from the greatest to least according to the strength of the linear relationship based on the given correlations.

r= 0.209r= -0.387r= -0.612r = 0.535

3.)The correlation between the size of an HDTV screen in centimeters and cost in dollars is r = 0.697. If the size in centimeters is converted in inches (1 in=2.54 cm), then what is the correlation between size in inches and cost in dollars?

4.)Given the following linear regression model, Temp = 30.4 – 0.72d, where temperature is measured in degrees Celsius and d is the distance from a heat source in centimeters, what is the residual of (6, 29.5)?

5.)A taxi company monitoring the safety of its cabs kept track of the number of miles tires had been driven (in thousands) and the depth of the tread remaining (in mm).

Depth / 11 / 11 / 11 / 9 / 9 / 8 / 3
Miles / 6 / 7 / 8.5 / 9 / 9.5 / 15 / 30

a.)Sketch a scatterplot. Label the axes with appropriate titles.

b.)Describe the relationship between the variables in context.

c.)What is the response variable?

d.)Write the regression. Use 3 decimal digits for a and b.

e.)Find the linear correlation coefficient

f.)Find the coefficient of determination

6.)The length of the initial drop (in feet) and the duration (in seconds) of a roller coaster ride can be modeled by the following equation.

Duration = 0.242(Drop) + 91.033

a.)Interpret the slope of this model in context.

b.)Calculate the percentage of variation for this problem assuming r = .793. What does this mean in context of the problem?

7.)At the University of Pittsburgh, every student gets a college e-mail address. Data collected by the college showed a negative association between student grades and the number of e-mails the student sent during the semester.

  1. Explain what “negative association” means in this context.
  2. After seeing this study, the college proposes trying to improve academic performance by limiting the number of e-mails that students can send through the college address. As a statistician, what do you think of this plan? Explain briefly.

8.)Below are serving sizes and calories of 6-inch sandwiches at Subway.

Sandwich / Serving Size (grams) / Calories
Chicken Bacon Ranch / 299 / 570
Philly Cheesesteak / 311 / 520
BLT / 164 / 360
Cold Cut Combo / 252 / 410
Italian BMT / 245 / 450
Meatball Marinara / 379 / 580
Spicy Italian / 240 / 520
Subway Melt / 256 / 380
Tuna / 252 / 530

a.)Create a scatterplot using serving size as the explanatory variable.

b.)State the regression line. And then graph the line on the scatter plot.

c.)Test the claim that serving size of subways sandwiches and the calories of the subs have a significant linear correlation.

d.)Predict the value of a sub that would have a serving size of 300 grams.

e.)Find the 95% prediction interval for the calories of a serving size of 300 grams.