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  • - [Instructor] 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.

  • And 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 wanna figure out

  • what time is being told by each of these clock faces.

  • So let's go here on the left.

  • So the first thing I'm gonna 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.

  • Six-something.

  • And 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?"

  • And I like to count by fives

  • because we know when we go from 12 on the clock to one

  • that actually one, two, three,

  • four, five minutes have gone by.

  • And in fact, between any two numbers, it's five minutes.

  • So we go five, 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.

  • And then where we're ending, let's see.

  • The hour hand is a little bit past nine.

  • You can see it's past nine.

  • And so it's not necessarily

  • what it's closest to, it's what it's past.

  • 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 gonna be nine-something."

  • It's passed nine.

  • And only if it got to 10 or past 10,

  • then you would say, "It's 10-something."

  • So this is gonna be nine-something.

  • And to figure out what that something is,

  • once again, we start here, we can count by fives.

  • Five minutes, 10 minutes, and then we have one more.

  • We get to 11 minutes.

  • So it's 9:11.

  • And 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.

  • And so we can set up a timeline here.

  • So let's set up a timeline.

  • And so, let's see.

  • The sixth hour is going to be important,

  • so that's six o'clock.

  • And let's see, maybe we wanna go all the way to 10 o'clock.

  • So that we go beyond 9:11.

  • And so then we could say, let's go,

  • have to do seven, eight, and nine.

  • I just wanna get my spacing right.

  • So let's say that this is seven o'clock right over here.

  • This is eight o'clock right over there.

  • And then that is nine o'clock right over there.

  • It's not gonna be a perfect drawing,

  • but this is pretty close.

  • And so let's 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.

  • And 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 seven 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.

  • Just write it out.

  • And 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.

  • 11 minutes.

  • So how much time has happened?

  • It's going to be 17 minutes plus two 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 28 minutes.

  • And I could write it that way.

  • Two hours, two hours and 28 minutes.

  • And we are done.

- [Instructor] We are asked, "How much time has passed

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A1 初級

兩個鐘面之間的時間過去了 (Time past between two clock faces)

  • 3 0
    林宜悉 發佈於 2021 年 01 月 14 日
影片單字