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### Unit 4: Lesson 1

Rate problems with fractions

# Rates with fractions

Sal solves an example problem with rates with fractions.

## Want to join the conversation?

• What happens if there is a fraction that's like 4 3/4??
• you change the mixed number to a improper fraction 4 3/4=19/4
• What is a reciprocal?
Is it just the reverse of something?
• The reciprocal of a fraction is it flipped. For example, the reciprocal of 1/5 is 5/1 (which is 5.)
The reciprocal of an integer, is 1 divided by the integer. For example, the reciprocal of 5 is 1/5 and the reciprocal of 98 is 1/98
• is any other way
• You know the rule of fraction divide .as2/3 devide by4/ 5 =2/3 multiply5/4 .=10/12 =5/6 answer .
• I'm so confused...why am I dividing
• Since the question is asking "how many bottles will it take to clean the bathroom (or how many fractions of a bottle) " you need to divide the number of bottles per bathroom.
"per" just means divide.
Its like saying "I have 10 pickles and 2 jars. how many pickles will it take to fill each jar?"
simple, divide the number of pickles by the number of jars.
Except in the video, there are no pickles, and no jars. Instead, there are bottles of soap and bathrooms.
• What if you were to do it flipped around like bathroom/bottles could that sill work?
• No, it would not because ratios are like fractions and if we could switch numerators and denominators, 2/1 would equal 1/2, when 2 is greater than 1/2
• Did anyone else find the answer a different way then he did? I actually made 3/5 into 1 fifths by dividing it by 3. I did the same thing to 1/3 and got 1/9. Then, since I knew 5/5 is a whole, I multiplied 1/9 times 5 and got 5/9 as my final answer. Sorry if this is really long. I just want to find out if the way I did it was the way some other people may have done it.
• I did it a bit different. I wanted to turn 3/5 of a bathroom into 1 whole bathroom so I multiplied it by 5/3. I did the same thing to 1/3 to keep the equation equal which gave me 5/9 of a bottle.
(1 vote)
• why was Sal able to divide 1/3 by 3/5 to figure out how much of the bottle it would take to clean one bathroom? I thought he would have to use (1/3) / (3/5) as a beginning proportion, and then multiply both by 5/3 to figure out how many bottle it would take to clean an entire bathroom. Dividing 1/3 by 3/5 seems arbitrary to me.
• I NEED HELP. Ruben is buying bricks for a project. He knows that 5 bricks weigh 26 1/4 pounds. He wants to know the weight of 24 bricks. What is the weight per brick?
• Well, 5 bricks weigh 26 1/4 pounds, so the answer is 26 1/4 (85/4) / 5, which is 17/4, or 4 1/4 pounds per brick.
Note: The phrase "He wants to know the weight of 24 bricks" is actually useless.
Hope this helps