Exam 7: Correlation and Causality

To get the best deal on a microwave oven, Amanda called six appliance stores and asked the cost and volume of several models. The prices and volumes she was quoted are listed below. Construct a scatter diagram for the data. $\begin{array}{l}\begin{array} { c c } \hline \text { Volume (cu.ft) } & \text { Price (\$) } \\\hline 1.8 & 417 \\1.5 & 463 \\1 & 200 \\1.5 & 17 \\0.7 & 49 \\1.5 & 349 \\1.9 & 183 \\0.5 & 119 \\2.2 & 119 \\\hline\end{array}\\\text { - }\end{array}$

Answer the question using the value of r and the given best-fit line on the scatter diagram. - The scatter diagram and best-fit line show the data for price per item (y)and the availability of that item (x). The correlation coefficient r is -0.95. Predict the price per item for an availability of 3.

Select the best estimate of the correlation coefficient for the data depicted in the scatter diagram. -

Solve the problem. -The table below shows the legal costs and the profits of a company from 2000 to 2005. Construct a scatter diagram for the data and state whether legal costs and profits for this company have no correlation, a positive correlation, or a negative correlation for this period. $\begin{array} { c c c } & \text { Legal Costs } & \text { Profits } \\\text { Year } & \text { (Millions of \$) } & \text { (Millions of \$) } \\2000 & 9 & 9 \\2001 & 14 & 6 \\2002 & 12 & 8 \\2003 & 11 & 14 \\2004 & 15 & 9 \\2005 & 10 & 15\end{array}$

Solve the problem. Round your answers to the nearest whole percent. - The scatter diagram shows the data for the number of cars waiting by a school (y) and the amount of time after tl of classes (x). The correlation coefficient $\mathrm { r }$ is $- 0.55$ . Determine how much of the variation in the number of wait cars can be accounted for by the best-fit line.

State whether you believe the two variables are correlated. If you believe they are correlated, state whether the correlation is positive or negative. -Time spent walking and distance covered

Write possible coordinates for both outliers so that neither would be an outlier.

State whether you believe the two variables are correlated. If you believe they are correlated, state whether the correlation is positive or negative. -The age of a car and its fuel efficiency.

How does the outlier affect the correlation coefficient?.

Construct a scatter diagram with two groups of data, correlations within each group, but no correlation among all the data.

Write the coordinates of a point that would be an outlier on the following graph.

Solve the problem. Round your answers to the nearest whole percent. - The scatter diagram shows the data for attendance at the local team's hockey games (y)and the number of wins (x)for That team. The correlation coefficient r is 0.4. Determine how much of the variation in attendance can be accounted for By the best-fit line.

Determine whether the stated causal connection is valid or not valid. -Long-distance hikers sometimes get blisters on their feet.

Determine whether the stated causal connection is valid or not valid. -The distance that a hit golf ball travels is caused by the strength of the golfer.

State whether there is no correlation, a positive correlation, or a negative correlation between the x and y variables. If there is a correlation, state whether it is most likely due to coincidence, a common underlying cause, or a direct cause. - For a group of English students at the local junior college, the scatter diagram compares the number of correct answers on a test they took(y)and the length of the pencil used to take the test(x).