# Practice for test 4 worksheet

```JMJ
For # 1 – 10 write the answers on the space provided. Each question is worth 5 points.
# 1-3 Use these answer choices:
a) Positive Correlation
b) Negative Correlation
c) No Correlation
1) What type of correlation does this graph show?
1. ________________
2) What type of correlation does this graph show?
2. ________________
3) What type of correlation does this graph show?
3. ________________
# 4-8 Use the following choices to describe the correlation coefficient.
a) none b) weak
c) moderate
d) strong
e) positive
4)
5)
6)
7)
8)
r = 0.72
r = -0.31
r = 0.89
r = 0.11
r = - 0.99
9) In the equation y = ax + b the b represents?
a) slope
b) y-intercept
f) negative
4. ________________
5. ________________
6. ________________
7. ________________
8. ________________
c) correlation coefficient
9. ________________
d) variability
JMJ
Use the following information for this question. It is worth 25 points.
10) The following table gives the gold medal winners for the four-man bobsled teams in the Olympics
from 1964 to 2010.
Year
Time(in minutes)
1964
4.14
1968
2.17
1972
4.43
1976
3.40
1980
3.59
1984
3.20
1988
3.47
1992
3.53
1994
3.27
1998
2.39
2002
3.07
2006
3.40
2010
4.76
a) Create a scatter plot with x = 4 corresponding with 1964.
X Min _____________
Y Min ___________
X Max ____________
Y Max ___________
X Scl _____________
Y Scl _____________
b) Use a regression feature to find an equation of best fit. Linear or Quadratic _________________________
Write the equation of best-fit ______________________________________
c) Using the equation of best-fit to predict the best time for the Olympics in 2014 _____________________
d) What is the coefficient of determination? ________________________
e) What is the correlation coefficient? _________________________________________
f)
What type of correlation does this graph have? ______________________________________________
JMJ
Use the following information for this question. It is worth 25 points.
11) Healthcare costs have been increasing over the years. The following data shows the average cost
of healthcare per person from 1976 to 1998:
Year
Cost(per person)
1976
618
1980
860
1987
1324
1993
1896
1998
2256
a) Create a scatter plot with x = 6 corresponding to 1976.
X Min __________ Y Min ___________
X Max __________ Y Max ___________
X Scl ___________ Y Scl ____________
b) Find an equation of a line that best fits ______________________________________________________________
c) Is the line that best fits a linear model or quadratic model? _______________________________________
d) Using the best fit model, when will healthcare reach \$2800 a person? ___________________________
e) Between which two years from the chart have the greatest percent increase? __________________
f)
According to the best fit model, what is the health care cost for the year 2013? ________________
```