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Current time:0:00Total duration:3:58

CCSS.Math:

we've got some apples here and we've got some oranges and what I want to think about is what is the ratio what is the ratio of apples of apples to oranges to oranges and to clarify what we're even talking about a ratio is giving us the relationship between quantities of two different things so there's a couple of ways that we can specify this we can literally count the number of apples 1 2 3 4 5 6 so we have 6 apples and we could say the ratio is going to be 6 - 6 - and then how many oranges do we have 1 2 3 4 5 6 7 8 9 it is 6 to 9 ratio of apples to oranges is 6 to 9 and you could use different notation you could also write it this way 6 - you would still read it is the ratio is being 6 to 9 but we don't have to just satisfy us with this because one way to think about ratios if we're especially for thinking about apples to oranges is how many apples do we have for a certain number of oranges and when you think about it that way we can actually reduce these numbers as you might have already thought about both 6 & 9 are divisible by 3 so just how like we can reduce fractions we can also reduce ratios so if you divide 6 and 9 both by 3 6 divided by 3 is 2 6 divided by 3 is 2 and 9 divided by 3 is 3 so we could also say that the ratio of apples to oranges is 2 to 3 or if we want to use this notation - 2 3 2 2 3 now does that make sense well look we divided each of these groups into three so one way to think about it so if you divide if you divide this whole total into 3 groups so one group one group two groups two groups and three equal groups we see that in each of those groups for every two apples for every two apples we have three oranges for two apples we have three oranges for two apples we have three oranges so once again the ratio of apples to oranges for every two apples we have three oranges but we could think about things the other way around as well we could also think about what is the ratio we could also think about what is the ratio ratio of oranges to apples oranges to apples and here we would essentially switch the numbers the ratio of oranges to apples notice up here we said apples to oranges which is six to nine or two to three if we reduce them and here we're going to say the ratio of oranges to apples so we've swapped these two and so we're going to swap the numbers here we have nine oranges for every six apples so we could say the ratio is going to be nine to six the ratio is 9 to 6 or if we want to reduce it for every three oranges so we're going to divide this by three so for every three oranges we are going to have two apples we are going to have two apples so notice this is just exactly what we had up here but when we had apples to oranges it was 6 to 9 6 apples for every 9 oranges and now when it's oranges to apples we say it's nine two six nine oranges for every six apples or we could say for every three oranges we have exactly two apples