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

1.  If your total earnings up to week 8 are 69.72213 dollars, and your total earnings up to week 15 are 78.72213 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 118.4652 dollars, then what will be your total earnings that the end of week 14?

3.  If your total earnings up to week 6 are 72.36927 dollars, and if you earn money at a constant rate of 13 dollars per week, then at what week will your total earnings be 85.36927 dollars?

4.  If an automobile is at milepost 486.2273 after having traveled for 9 hours and at milepost 541.2273 after having traveled for 19 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 63 mph, and is at milepost 246.8412 after having traveled for 4 hours, then what milepost would be after having traveled for 14 hours?

6.  If an automobile is traveling at the rate of 57 mph, and is at milepost 434.9753 after having traveled for 8 hours, then after how many hours of travel will it have reached milepost 15?

7.  If the water in a uniform cylinder has depth 129.6353 cm at clock time 10 seconds and depth 143.6353 cm at clock time 19 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 28 cm/second between clock times 8 s and 15 s, and if its depth at clock time 8 seconds is 215.7038 cm, then what is its depth at clock time 15 seconds?