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Proportions and Rates

Added Oct 25, 2013 •

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This video will show you how to solve proportion problems using the strategy of (1) cross multiplying (2) then dividing

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let's go ahead and get our pencils ready today we are going to go over rates and proportion if you saw the meow video do you have an idea what race are rate is simply put comparison that can't see that color a comparison 02 different quantities  and this little school bus right here is a little glimpse of what we're going to show you in a bit proportion if you guys saw the word wall thanks for the Smartboard a proportion is simply put to equal fractions but we're going to vocabulary two equal ratios Centennial going to cover rates and proportions and I'm going to go ahead and posit there for a couple seconds before we can immune oh I hear something you can see the school bus was coming right at you and it was traveling in miles per hour so the rate where complain today are miles an hour and we have this problem here which reads a bus driver travels 420 miles every 7 hours drives at a constant rate of change how many miles will he travel in 2 hours  Stop we're going to go ahead and posit here that way you guys can copy the problem and go ahead and dry your little school bus and the word comparing at the bottom and will continue in a bit it's that time again intermission is over okay so what are we comparing want you to get your highlighter should have a highlighter and I want you to actually  I think I have a highlighter in myself straight the song wanted a high-level were comparing and we're comparing miles 2 hours so after you wrote that down next to comparing you're going to ride miles  per hour her miles per hours miles to hours Asbury comparing  okay let's make our frustration what's we have 420 and 420 is a number of miles that are troubled in 7 hours  not we're trying to find out how much or how many miles he's in a travel 2 hours  you make it equal to another ratio that's equal to it hours will go down here in the bottom so we'll put two hours and we're trying to find out how many miles he's going to travel so I'm going to write Vermont  okay The Next Step happens really fast and yes it's that easy that look like a molecule or something that you see in chemistry we're going to cross multiply -20 + 2 and then whatever you get we divide my son stop 420  x 2 I'll go ahead and let you work that out and we're going to go ahead and posit here for a second okay hopefully you saw that you just have to double  420 I know that my double for I get 8 divide double the two I got four  and I mean baby double zero you going to get all right now the last step is to divide five seven how many groups of 7 can go into 8 one time  7 * 1  the seven the difference is one Brandon  4  how many groups of 7 can go into 4 two groups sound * 2 is 14  we have a remainder zero but you still have one digit right there so we're going to bring that down  how many sevens in going 2-0 goes there all times 7 times 0 muzo  and we have our answer  our answer is 120 121 number they were looking for what so the answer is that me two hours he will travel Route 20 that does it for  solving this problem okay so there is your answer what's that I hear night sorry about that got ahead of it okay so here is the question  Chow home turn off I'm pronouncing that right can run at a constant rate of 10 miles and 4 hours how many miles can you run in 1 hour go ahead and copy the question we're going to go ahead and posit here  here's the question  don't forget what's right what you are comparing at the bottom and that box get directions are to do the following  you're going to compare tell me what you're comparing then you're going to create a proportion how do you create a proportion you're going to cross  multiply then divide to get your answer so once again Step 1 and we're going to go ahead and put the steps in blue tell me what you're comparing  Step 2 create a proportion and step 3 cross-multiply then divide and we'll go ahead and pass it and we are back we want to hide that were comparing miles 2 hours miles came first or going to write miles 2 hours  step one for the easy nothing too hard about it that's what I want to step to let's create a proportion  proportion again is 2 equal what ratios hopefully you said ratios okay what came first in the sentence the 10 miles so you write 10 as a numerator then you write 4 in the bottom because ours goes in the bottom  no they wants to know how many can he run so that means we don't know how many miles so on top we put the letter M to represent miles and I wants to know in one hour so we're going to go ahead and put one this is simply a unit rate problem cuz you're trying to find how much you can do one hour step 3 cross multiply  let's go ahead and do our little possess here the product of 10 and 1 is 10 divide that by 4  and as we divide now you got to take your time and Division can 4 go into 1 no  however it goes into 10 the product of 4 and 2  it track 10-8 what's the difference  as you can see we still have a remainder or try to get a remainder of zero  so we need to borrow from the tens place now bring down that zero and then how many groups of 4 can go into 20  5/4 * 5 is 20  now we have a remainder of what the remainder is zero so that tells you that you can stop and our answer again is miles to my answer at the bottom needs to be house  any answers two and a half Grandpa's it here for a bit looks like we are done guys what did you learn well we learn how to cross multiply provide when using a proportion so go ahead and write that down this will be part of your exit ticket when stopping a proportion you can cross multiply and divide what else did you learn before making up report you need to know what you are comparing  so don't get ahead of yourself don't start crunching numbers if you don't even know what you're comparing it salsa for making up a portion know what you are comparing last but not least we learned  the chow hall is terribly terribly slow  best metal cutter for today guys

Uploaded by Jorge Zuniga.

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