Final answer:
The hourly decrease in the swimming pool's water level is approximately 0.048 inches per hour from 10 P.M. to 7:20 A.M., assuming a constant decrease of 4/9 inch over 9.33 hours.
Step-by-step explanation:
The student has asked how much the water level in a swimming pool decreased each hour between 10 P.M. and 7:20 A.M., assuming it decreased by a total of 4/9 inch during that time and did so at a constant rate. To solve this, we first calculate the total number of hours between 10 P.M. and 7:20 A.M. This is a total of 9 hours and 20 minutes, which can be converted to 9.33 hours (since 20 minutes is 1/3 of an hour). Using this information, we can determine the rate of decrease per hour by dividing the total inches dropped by the number of hours.
To find the hourly rate, divide 4/9 inch by 9.33 hours which equals approximately 0.048 inches per hour. Therefore, the swimming pool's water level decreased by about 0.048 inches each hour between 10 P.M. and 7:20 A.M.