TIME PRACTICE

Concept: We divide a day into 24 equal parts called hours. Each hour is divided into 60 equal lengths of time called minutes, and each minute is divided into 60 seconds. Most clocks resemble one of the two clocks in the picture above, and are either 12 hour clocks or 24 hour clocks. Our questions in this section are based on 12 hour clocks, like the ones in the picture above, and the questions will specify AM or PM. Our questions in this section ask how much time has elapsed from Start Time to Stop Time. Determine how much time has elapsed by finding the difference between the Start Time and the Stop Time.

STEPS FOR FINDING DIFFERENCES BETWEEN TIMES

Step 1 | Begin at the Start Time.
Step 2 | Begin with the minutes. Advance from the Start Time to the Stop Time. Note how many minutes elapsed between the two marks. If the Start Time minute is larger than the Stop Time minute, you will need to subtract one hour from the hours elapsed in Step 3.
Step 3 | Continue with the hours. Advance from the Start Time to the Stop Time. Note how many hours elapsed between these two marks. If the Start Time minute is larger than the Stop Time minute in Step 2, subtract one hour from the hours elapsed.
Step 4 | List the hours elapsed (Step 3), followed by the minutes elapsed (Step 2), separating the hours from the minutes with a colon.

Example 1 Find the time difference: Start Time 11:10 AM Stop Time 1:10 AM

Step 1 | Begin at the Start Time. | 11:10 AM
Step 2 | Begin with the minutes. Advance from the Start Time to the Stop Time. Note how many minutes elapsed between the two marks. | Start Time 00:10 Stop Time 00:10 Minutes elapsed 00:00
| If the Start Time minute is larger than the Stop Time minute, you will need to subtract one hour from the hours elapsed in Step 3. | Does not apply.
Step 3 | Continue with the hours. Advance from the Start Time to the Stop Time. Note how many hours elapsed between these two marks. | Start Time 11 AM Stop Time 1 AM
| From 11 AM to 11 PM there are 12 hours that elapse. From 11 PM to 1 AM there are 2 hours that elapse. Combine 12 hours and 2 hours to equal 14 hours. | Start Time 11 AM Stop Time 1 AM Hours elapsed 14 hrs
| If the Start Time minute is larger than the Stop Time minute in Step 2, subtract one hour from the hours elapsed. | Does not apply.
Step 4 | List the hours elapsed (Step 3), followed by the minutes elapsed (Step 2), separating the hours from the minutes with a colon. | 14:00 hours elapsed between 11:10 AM and 1:10 AM.

Example 2 Find the time difference: Start Time = 11:25 PM Stop Time = 6:15 PM

Step 1 | Begin at the Start Time. | 11:25 PM
Step 2 | Begin with the minutes. Advance from the Start Time to the Stop Time. Note how many minutes elapsed between the two marks. | Start Time 00:25 Stop Time 00:15
| To advance from 25 minutes after the hour to 60 minutes [the end of the hour], 35 minutes elapse. To advance from 0 minutes [the beginning of the hour] to 15 minutes after the hour, 15 minutes elapse. Combine 35 minutes and 15 minutes to equal 50 minutes. | Start Time 00:25 Stop Time 00:15 Minutes elapsed 00:50
| If the Start Time minute is larger than the Stop Time minute, you will need to subtract one hour from the hours elapsed in Step 3. | 25 is larger than 15.
Step 3 | Continue with the hours. Advance from the Start Time to the Stop Time. Note how many hours elapsed between these two marks. | Start Time 11 PM Stop Time 6 PM
| From 11 PM to 11 AM there are 12 hours that elapse. From 11 AM to 6 PM there are 7 hours that elapse. Combine 12 hours and 6 hours to equal 19 hours. | Start Time 11 PM Stop Time 6 PM Hours elapsed 19 hrs
| If the Start Time minute is larger than the Stop Time minute in Step 2, subtract one hour from the hours elapsed. | Since 25 is larger than 15, subtract 1 hr from 19 hrs. Hours elapsed = 18 hrs
Step 4 | List the hours elapsed (Step 3), followed by the minutes elapsed (Step 2), separating the hours from the minutes with a colon. | 18:50 hours elapsed between 11:25 PM and 6:15 PM.