Final answer:
To complete all tasks by 9pm, you should start at 7pm, as it takes a total of 2 hours to complete all the tasks when calculated step-by-step.
Step-by-step explanation:
To solve the time management problem mentioned in the question, we need to calculate the total time required to complete all tasks and then work backwards from the 9pm deadline to determine the latest start time.
Step-by-step Explanation:
- First, convert all the durations of the tasks into minutes: 15 minutes at the post office, 1 hour and 25 minutes at the mall convert to 85 minutes, and 20 minutes driving.
- Add up all the minutes: 15 + 85 + 20 = 120 minutes.
- Convert the total minutes back into hours, where 60 minutes equals 1 hour, resulting in 120 minutes being equal to 2 hours.
- Since all the tasks must be completed by 9pm, subtract 2 hours from 9pm, which indicates that the latest start time is 7pm.
Therefore, to finish all tasks by 9pm, one should start at 7pm at the latest.