Unit 2 Review

____ 1. Which headline describes a situation with a negative correlation?

A / Increase in teen drug use decreases the high school graduation rate
B / Lack of sleep decreases productiveness at work
C / Cities with higher unemployment rates show evidence of higher murder rates
D / SAT scores improve in areas with more availability to SAT prep courses

____ 2. Which headline describes a causal relationship?

A / Anxiety levels lower test performance in high school students
B / Video game use causes decline in grades of college students
C / Increase in number of recreational sports helps curb child obesity
D / Alcoholism linked to lung cancer

____ 3. The linear model for the amount of Federal Minimum Wage (where x represents the number of years after 1955) is . Which statement most accurately describes the meaning of the slope?

A / Minimum wage increases thirty cents per year after 1955.
B / Minimum wage decreases thirty cents per year after 1955.
C / Minimum wage increases twelve cents per year after 1955.
D / Minimum wage decreases twelve centers per year after 1955.

____ 4. Using the Federal Minimum Wage model from question 11, what is the most accurate interpretation of the y-intercept?

A / The starting minimum wage was $0.12.
B / The minimum wage in 1955 was $0.12.
C / The starting minimum was was $0.30.
D / The minimum wage in 1955 was $0.30.

5. The table below shows the winning times for the Women’s 100-Meter Freestyle swims in the Summer Olympics since 1972. Find the equation for best-fit line, letting x represent the number of years after 1972.

1972 / 1976 / 1980 / 1984 / 1988 / 1992 / 1996 / 2000 / 2004 / 2008
58.59 / 55.65 / 54.79 / 55.92 / 54.93 / 54.64 / 54.50 / 53.83 / 53.84 / 53.12

Answer each of the following questions:

a. What is the slope of the best-fit line? / b. What is the y-intercept of the best-fit line? / c. What is the correlation coefficient of the best-fit line? / d. Predict the winning time for the 2012 Olympic Games.

The table below shows the actual data from the results of the Women’s 200-Meter Dash at the Summer Olympic Games from 1948-2004.

6. Create a scatter plot using the table below.
Choose an appropriate scale and label all axes. (6 points)

Year / Time (seconds)
1948 / 24.40
1952 / 23.89
1956 / 23.55
1960 / 24.13
1964 / 23.05
1968 / 22.58
1972 / 22.40
1976 / 22.37
1980 / 22.03
1984 / 21.81
1988 / 21.34
1992 / 21.81
1996 / 22.12
2000 / 21.84
2004 / 22.05

7. a) Find the line-of-best-fit. Round to the nearest hundredth. (3 points)

______

b) Interpret the slope and y-intercept using complete sentences. (4 points)

c) State the correlation coefficient and describe the correlation. (3 points) r = ______

Draw Scatter Plots and Best-Fitting Lines

11. Plot the data in the grid: a) Graph the data on the grid below

X = number of seconds / Y = number of marshmallows eaten
1 / 1
2 / 2
3 / 2
4 / 3
5 / 4
6 / 18
7 / 5
8 / 6
9 / 7

b) Describe the correlation of the scatterplot.______

c) Use “eyeballing” to estimate the best-fit line of your data. Draw it on your graph and write the equation below:

d) Use your calculator to find the Linear Regression

Line______

e) correlation coefficient r = ______from your calculator.

Interpret the r value:______

f) Interpret the slope of the regression line (in context):

g) Interpret the y- intercept of the regression line (in context):