D) Determining the Interval between   Two given Times

Interval is the length of time between two given 

times.

Worked Example 35

Find the interval between 09.15 a.m. and 3. 45 p.m.

on the same day.

Solution

Interval

= 2 hours 45 minutes + 3 hours 45 minutes

= 6 hours 30minutes

Worked Example 36

Find the interval between 11. 30 p.m. on Tuesday 

and 4. 15 a.m. on Wednesday.

Solution

Interval

= 30 minutes + 4 hours 15 minutes 

= 4 hours 45 minutes

E) Determining the Time in the 12-hour  System or 24-hour System

Worked Example 37

Find the time which is 5 hours 25 minutes after 

2. 15 p.m., in the 12-hour system.     Solution

The time is 7. 40 p.m..

Worked Example 38

Find the time which is 5 hours 55 minutes before

2. 10 p.m., in the 12-hour System.

Solution

2. 10 p.m. = 1410 hours

     

The time is 8. 15 a.m..

Worked Example 39

Find the time which is 4 hours 50 minutes after

2120 hours, in the 12-hour system.     Solution

    The time is 0210 hours, the next day.

F) Problem Solving involving Time

A show starts at 8. 45 a.m. and ends at 3. 20 p.m.

How long is the show?   

Solution

1. Understand the problem

    Given information :

    The show starts at 8. 45 a.m..

    The show ends st 3. 20 p.m..

    Find : Duration of the show

2. Devise a plan

    Change the times to the 24-hour system and 

    then use subtraction.

3. Carry out the plan 

    8. 45 a.m. = 0845 hours

    3. 20 p.m. = 1520 hours

        

    Therefore, the show lasts 6 hours 35 minutes.

4. Check