For Exercises 13–20, do the following for the indicated data set:

  1. Construct a scatterplot of the relationship between and .
  2. Interpret the scatterplot.
  3. Calculate the correlation coefficient .
  4. Interpret the value of the correlation coefficient .

Question 4.19

19. The cost of a repair job, and the number of hours spent on the repair:

Cost Hours
120 2
180 3
230 5
350 8
380 10

4.1.19

(a)

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(b) The hours a repair job takes and the cost of the repair job have a positive linear relationship. (c) (d) This value of is very close to the maximum value . We would therefore say that hours worked and cost are positively correlated. As the number of hours worked increases, the cost also tends to increase.