Time past between two clock faces

We are asked how much time has passed from the time on the left, so right over here, to the time on the right, which we see right over here. They say that the time passed is less than 12 hours. So like always, pause this video and see if you can answer that on your own before we work on this together.

All right, so first I just want to figure out what time is being told by each of these clock faces. So let's go here on the left. The first thing I'm going to do is look at the hour hand, and we can see that the hour hand has gone a little bit past six. So it's going to be six something.

Then to figure out what the minutes are, I can look at the minute hand right over here and say, well, how far has it gone in minutes? I like to count by fives because we know when we go from 12 on the clock to 1, that actually 1, 2, 3, 4, 5 minutes have gone by. In fact, between any two numbers, it's five minutes.

So we go 5, 10, 15, 20, 25, 30, 35, 40, and then 41, 42, 43. That's where it's pointing, so it's 6:43 is where we're starting.

Then where we're ending, let's see, the hour hand is a little bit past 9. You can see it's past nine, and so it's not necessarily what it's closest to; it's what it's passed. So even if the hour hand was like there, even if it was closer to 10 but not quite at 10, you would say, okay, it's going to be 9 something. It's past nine.

Only if it got to 10 or past 10, then you would say it's 10 something. So this is going to be 9 something. To figure out what that something is, once again we start here; we can count by fives: 5 minutes, 10 minutes, and then we got, we have one more, we get to 11 minutes. So it's 9:11.

They tell us that this is less than 12 hours apart. So it's not like 6:43 in one day, maybe at night, and then 9:11 the next morning. This is maybe the same morning or the same evening.

We can set up a timeline here. So let's set up a timeline. Let's see, the sixth hour is going to be important, so that's six o'clock. Maybe we want to go all the way to 10 o'clock so that we go beyond 9:11.

We could say, let's see, we'll have two, 7, 8, 9. I just want to get my spacing right, so let's say that this is 7 o'clock right over here; this is 8 o'clock right over there, and then that is 9 o'clock right over there. It's not going to be a perfect drawing, but this is pretty close.

See, we are starting at 6:43, which is going to be, let's see, it's going to be roughly, and I just have to say roughly, it's going to be right over there; that's where we are starting. Then 9:11 is going to be roughly right over there, so that is when we are ending.

So how much time has gone by? Well, to go from 6:43 to 7 o'clock, how many minutes is that? Well, to go from 43 minutes to 60 minutes, you have to add 17 minutes. So this right over here, that is 17 minutes; I'll just write it out.

Then we can see we have another two hours that goes by from seven o'clock to nine o'clock. So then that's two hours. And then to go from nine o'clock to 9:11, what is going on? Well, that's going to be another 11 minutes.

So how much time has happened? It's going to be 17 minutes plus 2 hours plus 11 minutes. Well, I find it a little bit easier just to think about the minutes first. So if I add 17 minutes to 11 minutes, 17 plus 11 is 28. I can do that on the side if you want to see it: seven plus one is eight; one plus one is two.

So we are going to have a total of two hours and twenty-eight minutes. I could write it that way: two hours, two hours and 28 minutes, and we are done.