Exam 6: Scatterplots, association, and Correlation

A reporter studied the causes of a fire to a house,and established thanks to a scatterplot a strong correlation between the damages (in dollars)and the number of firefighters at the scene.Find the lurking variable,if there is one.

The table shows the number of years of teaching experience for 9 certified high-school teachers and their weekly salaries (in dollars).

A study shows that the amount of chocolate consumed in Canada and the number of automobile accidents is positively related.Find the lurking variable,if there is one.

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.

A reporter investigates speeding on roads in a county and finds a correlation of 0.961 between the number of speeding tickets and the numbers of kilometres of well-paved roads.Assuming that the relation is linear,does it mean that there are more speeding tickets on well-paved roads?

Data collected from 20 students in Statistics classes included their heights (in inches)and weights (in pounds),and are displayed in the following scatterplot.Make a histogram of the weights of the children.

Adam would like to buy a used car,and collected several data to evaluate the best model (such as age,price,weight,etc. )Thanks to a scatterplot,he established that the relation between age and weight is somewhat linear.He calculated that the correlation between age and weight is 0.515.Describe the association.

A teacher studied students' grades and established with a scatterplot a strong correlation between SAT scores and college grades.Find the lurking variable,if there is one.

Several scatterplots are given with calculated correlations. Which is which? -4) a)-0.921,b)-0.449,c)0.002,d)0.794

An economist noticed that nations with more TV sets have higher life expectancies.He established with a scatterplot a high positive correlation between length of life and number of TV sets.Find the lurking variable,if there is one.

Determine whether the scatterplot shows little or no association, a negative association, a linear association, a moderately strong association, or a very strong association (multiple associations are possible). -

Several scatterplots are given with calculated correlations. Which is which? - a)0.037,b)-0.445,c)0.003,d)-0.004

Two different tests are designed to measure employee productivity and dexterity.Several employees are randomly selected and tested with these results.

A survey was conducted in 20 counties to determine the percentage of teenagers who had used marijuana and other drugs.Data shown on the following scatterplot indicate a correlation of 0.972 between the percent of teens who have used marijuana and the percent who have used other drugs.Describe the association.