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Course: 6th grade (Illustrative Mathematics) > Unit 4
Lesson 3: Lesson 11: Using an algorithm to divide fractionsArea with fraction division example
Discover the length of a yoga mat with a width of 3/5 meters and an area of 1 and 2/25 square meters. Use the formula length = area ÷ width, convert mixed numbers to improper fractions, and simplify. The final dimensions are 3/5 meters wide and 9/5 meters long, perfect for your yoga practice! Created by Sal Khan.
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- I don’t get this can someone explain it to me?(13 votes)
- ANSWER: Okay, so since we know that l x w = A or A = l x w. To get the width, you would need to divide the Area which in this example was 1 2/25 m^2 (^ = power symbol) and the width which was 3/5 m. This would be written as 27/25 x 5/3 because 1 x 25 + 2 = 27 and the denominator is 25 and we flip the second fraction when dividing so this is why. Next, we can cancel out 27 and 3 by dividing by 3 and 25 and 5 by dividing by 5. After that you would get 9 x 1 in the numerator and 5 x 1 in the denominator. Then you would get 9/5 as the length. At this point you could stop here, but keep reading if you want to know why this works. First, make a rectangle and draw 9 equal sections, than spilt it into 3 equal sections horizontally. Now, since there are 9 squares in each row and we have 9/5, (remember, we are showing the area now) each square is 1/5 of a meter, on the length and width, then, each square is 1/25 square meters and there is 27 squares, 1/25 x 27 is 27/25.
Hope this helps!(2 votes)
- KCF is pretty helpful.(8 votes)
- i thought you said kfc(3 votes)
- im just doing while vibing to music(7 votes)
- 27/25
27/25 divided by 3/5 is 9/5 so the length is 9/5(6 votes)- Well, not really. 27/25 is the simplest form of this fraction. Try dividing to figure out the decimal quotient.(3 votes)
- Why does this stuff not help meee(5 votes)
- JUST DO KCF IT IS WAY ESIER (Keep first fraction Change divislon to multipication Flip do the reciprocal (8/1= 1/8) of the other fraction) then solve and BOOM answer given
credits to @#SlaySlaySlaySlayQueen👑(2 votes)
- this is confusing. are there any tips or tricks to help?(8 votes)
- JUST DO KCF IT IS WAY ESIER (Keep first fraction Change divislon to multipication Flip do the reciprocal (8/1= 1/8) of the other fraction) then solve and BOOM answer given
credits to @#SlaySlaySlaySlayQueen👑(0 votes)
- This is confusing 😪 am going to fail cause I don’t understand ❌ my mom is taking my phone away cause of this app 😭😭(4 votes)
- JUST DO KCF IT IS WAY ESIER (Keep first fraction Change divislon to multipication Flip do the reciprocal (8/1= 1/8) of the other fraction) then solve and BOOM answer given
credits to @#SlaySlaySlaySlayQueen👑(1 vote)
- math is easy but I do think the video is not understandable(4 votes)
- I am so confused right now i feel yalls pain im bouta fail this assignment(4 votes)
- I just noticed L = A DIVIDED BY W = L = L X W DIVED BY W.
Upvote for a cookie
(your choice of cookie)(4 votes)- You just noticed because of the video didn't you?(0 votes)
Video transcript
- [Instructor] We're told a
yoga mat is 3/5 of a meter wide. It has an area of 1
and 2/25 square meters. What is the length of the mat? Well, we know that length times width is going to give you area, or another way of thinking about it, if the product of two numbers
gives you a third number, if you take that third number and divide it by one of these, you're going to get the other one. So another way of thinking about it is length would be the same
thing as area divided by width. So we're trying to figure
out the length here. We have the area, we have the width. So our length is going to be 1 and 2/25, 1 and 2/25 divided by 3/5. Now this is going to be the same thing as, let me write this as an improper fraction, it's gonna be easier to do
some arithmetic with it. So one is the same thing
as 25/25, plus 2/25, this is 27/25 divided by 3/5. And we've already talked
about how this is saying how many 3/5 can fit into 27/25. And we've given the intuition
why this is the same thing as just multiplying 27/25
times the reciprocal of 3/5, which is 5/3. And so this is going to be equal to, and actually I'm gonna
factor this out a little bit to simplify things a bit. 27 is 3 x 3 x 3. 25 is 5 x 5. So this is going to be equal to, in our numerator we're
gonna have 3 x 3 x 3 x 5. 3 x 3 x 3 x 5. And then in our denominator
we're gonna have 5 x 5 x 3. 5 x 5 x 3. And then we can reduce this a little bit. We can divide both the numerator and the denominator by five. We can divide both the numerator and the denominator by three. So in the numerator, we're
gonna 3 x 3, which is 9/5. So this is all going to be equal to 9/5. So the yoga mat is 3/5 of a meter wide and 9/5 of a meter long. Now let's make sure that this makes sense. So I'm gonna make a grid. So this right over here is 1/5 of a meter. 1/5 of a meter in that dimension and 1/5 of a meter in that dimension. And then we can see, well,
if this is 1/5 of a meter, then the width right over
here is 3/5 of a meter. Our length right over
here, we have 1, 2, 3, 4, 5, 6, 7, 8, 9, fifths. It is 9/5. Now each of these units, what is its area? Well, it is 1/25 meter squared. And how many of these do we have? Well, we can see, we
have three rows of nine, which is 27 of these 25ths, so we're gonna have 27/25 square meters, which is the same thing as
1 and 2/5 square meters.