Start and finish times

Work out start and finish times, like when Jyoti goes out to play.

In your book, Maths Mela (Chapter 12), Jyoti goes out to play at 06:15 PM and comes back after 1 hour 45 minutes. When does she reach home? Add the hours first, then the minutes. 06:15 PM plus 1 hour is 07:15 PM. Now add 45 minutes: 07:15 PM plus 45 minutes. 15 + 45 = 60 minutes, which is a whole hour, so the time is 08:00 PM.

Sometimes we know the end time and must find the start. Ragini took 1 hour 10 minutes to do her homework and finished at 09:40 PM. Go backwards: 09:40 PM minus 1 hour is 08:40 PM, and 10 minutes earlier is 08:30 PM. So she started at 08:30 PM.

Watch out when the minutes go past 60. Lunch starts at 12:30 PM and lasts 35 minutes. 30 + 35 = 65 minutes, which is 1 hour 5 minutes. So lunch ends at 01:05 PM, not '12:65'. And a group of children leave for a picnic at 08:30 AM and return after 4 hours 10 minutes: 08:30 AM plus 4 hours is 12:30 PM, and 10 more minutes is 12:40 PM.

A long time can even carry us past midnight. It is 08:35 PM now. After 8 hours it will be 04:35 AM the next morning, and after 25 minutes more it will be 05:00 AM.

To find a finishing time, add the hours and then the minutes to the start time (60 minutes make 1 more hour); to find a starting time, take them away from the end time.

Practise this lesson

Questions that get harder as you improve, a Tutor that helps without giving the answer away, and progress you can see. Free for every learner.

Try it now Sign up free I have an account

No account, no email address. Opens the real product.