Question Video: Determining the Difference between the Given Times Mathematics • 5th Grade

Determine the difference between 10 hours, 29 minutes, and 8 seconds, and 6 hours, 20 minutes, and 30 seconds.


Video Transcript

Determine the difference between ten hours, twenty-nine minutes, and eight seconds and six hours, twenty minutes, and thirty seconds.

Now we need to remember that an hour consists of sixty minutes and a minute consists of sixty seconds. And there are several different ways of approaching this question, but let’s look at using a timeline to visualise the difference between these two times.

So six hours, twenty minutes, and thirty seconds is a smaller amount of time than ten hours, twenty-nine minutes, and eight seconds. So on our number line we represented that to the left. So the question is what’s the difference in time between these two times.

Well I’m gonna break this timeline down into manageable chunks. So if I start off at six hours, twenty minutes, and thirty seconds, thirty seconds later it would be six hours and twenty-one minutes. Then if I think what do I have to add to twenty-one to get up to the next sixty, that would be thirty-nine.

So thirty-nine minutes later, it would be seven hours. Then to get from seven till ten, that’s another three hours. And then from ten to ten hours, twenty-nine minutes, and eight seconds, I’ve got another twenty-nine minutes and eight seconds.

So to work out the difference in timing, I’ve got to add together all of these times that I had in that gap between six hours, twenty minutes, thirty seconds and ten hours, twenty-nine minutes, and eight seconds.

So first of all let’s consider the seconds. I’ve got thirty seconds here and I’ve got another eight seconds here. So that’s thirty-eight seconds in total there. Now that’s not more than a minute, so it’s just thirty-eight seconds. Next I’ve got thirty-nine minutes and twenty-nine minutes.

If I add thirty-nine to twenty-nine, nine and nine is eighteen, so that’s eight carry one; three and two is five and one is six. So that’s sixty-eight minutes, which is more than an hour, so it’s one hour and eight minutes.

So what I’ll do is I’ll add the hour to the number of hours and just use the eight minutes. And so finally moving onto the number of hours then, we had three hours between seven and ten plus the one hour that came from adding together all the minutes, and that makes a total of four hours. So our answer is the difference is four hours, eight minutes, and thirty-eight seconds.

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