Main content

## Measurement & Data - Statistics & Probability 189-200

### Course: Measurement & Data - Statistics & Probability 189-200 > Unit 3

Lesson 3: Elapsed time# Time differences example

Learn to find the difference between the times shown on two different analog clocks. Created by Lindsay Spears.

## Want to join the conversation?

- how many second can a hour have(12 votes)
- 3600 is the answer(22 votes)

- there are 86400 seconds in a day(17 votes)
- 31,449,600 in a year(16 votes)

- I always feel like these strategies are kind of long. Does anybody have a quicker strategy?(15 votes)
- no they are trying to leave you with no questions.(11 votes)

- Why do you have to go right and left for the video math?(9 votes)
- I'm not sure if I'm understanding you correctly, but are you asking why we have to know the difference between the clock on the right vs the clock on the left?

If so, just imagine that the clock on the left is a snapshot of the clock, and then some time later you take another snapshot of the clock and that is the clock on the right. Then you have to figure out how much time passed (elapsed) from one snapshot to the next.(8 votes)

- Jordyn left her house for school at6:30she stayed at school for 7 hours what time did she get home.(8 votes)
- i leave school at3:30so i really want that school period,i go to a charter school so it's like their trying to make us perfect.(4 votes)

- Time was created a veryyyy long time ago right? ;-;(7 votes)
- I don't really think it was created. When there was a big supernova, then maybe.(4 votes)

- how many mintes are in 2 hours(5 votes)
- A hour has 120 min as 60x2= 120 min(2 votes)

- There are 86,400 seconds a day.(4 votes)
- 1440 minutes in one day(1 vote)

- I know how to look at time on a clock but Not this thanks for the vid(4 votes)
- i dont understand(3 votes)
- 24h = 1d 1h = 60min 1min = 60sec 1sec = 1000 milisec(2 votes)

## Video transcript

- [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.