Solve the following by describing a picture, and by constructing a graph:

1.  If your total earnings up to week 7 are 87.12018 dollars, and your total earnings up to week 18 are 100.1202 dollars, then what are your average earnings per week? Why do we say average earnings per week rather than just earnings per week?

2.  If you are earning money at an average rate of 15 dollars per week, and if at the end of week 8 your total earnings are 112.2649 dollars, then what will be your total earnings that the end of week 16?

3.  If your total earnings up to week 6 are 47.22571 dollars, and if you earn money at a constant rate of 8 dollars per week, then at what week will your total earnings be 55.22571 dollars?

4.  If an automobile is at milepost 545.6852 after having traveled for 10 hours and at milepost 600.6852 after having traveled for 20 hours, then what is its average speed? Why do we say average speed rather than just speed?

5.  If an automobile is traveling at the rate of 37 mph, and is at milepost 281.3268 after having traveled for 8 hours, then what milepost would be after having traveled for 19 hours?

6.  If an automobile is traveling at the rate of 42 mph, and is at milepost 204.0814 after having traveled for 5 hours, then after how many hours of travel will it have reached milepost 15?

7.  If the water in a uniform cylinder has depth 119.6741 cm at clock time 7 seconds and depth 138.6741 cm at clock time 18 seconds, then at what average rate is the depth changing? What we say average rate rather than just rate?

8.  If the depth of water in a uniform cylinder is changing at an average rate of 17 cm/second between clock times 9 s and 15 s, and if its depth at clock time 9 seconds is 152.5549 cm, then what is its depth at clock time 15 seconds?