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Үндсэн товъёог
Цаг: 0:00Нийт үргэлжлэх хугацаа:4:03

Video transcript

how much time has passed from the time on the left to the time on the right so we have a clock on the left and clock on the right with different times shown and we want to know how much time has passed since the clock set read this first time till it read the second time we're also told the time passed is less than 12 hours that's helpful that means we know that this first clock wasn't say some time on Monday and the second one was sometime on Wednesday and these hands have been going around and around we know the time past is less than 12 hours so the first thing I think we should do to figure out the difference in these times is to figure out what are these times let's read these clocks over here on the left looking at our our hand first it's between 6 & 7 so the hour hand starts at the top and it's gone past 6 o'clock but it's not quite to 7 so it's 6 something could be 6:15 6:20 we'll figure out the minutes next but we know it's some amount of minutes after 6 but not yet 7 and now let's look at those minutes the minute hand again started at the top it's gone 5 minutes 10 15 20 25 30 35 40 can't go to 45 here so we gotta count by ones 41 42 43 it is 43 minutes after 6:00 o'clock or 643 on the left on the right our hour hand is just after the 9:00 so it's soon after 9:00 o'clock but it's definitely not 2:10 yet and then our minute hand right here start the top and it's 5 10 11 minutes after the hour on the right so the clock on the right is 9 11 and now what we want to know is how long does it take to get from this first time 6:43 all the way to the second time which is nine eleven one way we could figure this out is to break it into little parts let's first let's first just see how long does it take to get to 7 o'clock so in this first clock as soon as the minute hand gets up to the top it'll be seven o'clock let's see how long is that from here where it is it has two more minutes to get to the nine and then from there it has five ten fifteen more minutes to get all the way to the top of the clock so until seven o'clock will be two minutes plus fifteen more minutes or we can write that as 17 minutes then from seven let's stick with the hours for a second let's just get from seven to nine o'clock so from seven to nine at seven o'clock the hand is at the top it'll go all the way around one hour to the eight o'clock all the way around another hour to be nine o'clock so that's a total from seven to nine of two hours and then finally from nine until eleven minutes after nine the out the minute hand will be at the top and it'll go five ten eleven minutes so this will be eleven more minutes so in total from 643 all the way to nine eleven is 17 minutes plus two more hours plus eleven minutes so we can write that that's going to be two hours and then we can combine our minutes seventeen and eleven seventeen and eleven that will be eight ones a 10 and a 10 is 20 so 28 minutes it takes two hours and 28 minutes for the clock to go from 643 this time on the left until 911 the time on the right