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## Arithmetic

### Course: Arithmetic>Unit 10

Lesson 10: Multiplying fractions word problems

# Multiplying fractions word problem: muffins

Sal solves a word problem by multiplying 2 fractions. Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

• To solve, can't you also do 3/4 divided by 2? 3/4*1/2=3/8, right?
• Yes you can! Dividing by a number is the same as multiplying by its reciprocal. To find the reciprocal of a number we swap the numerator and denominator. Just be careful not to get confused when saying you divide a fraction by something. For example, you might accidentally do this:

``3/4 ÷ 23/(4÷2)3/2``

Which as you know isn't right!
• 7/24x20/21x9/10=
• 1/2 means half?? right or wrong
• Yes 1/2 and half are the same thing. They are both one half.
(1 vote)
• in multiplying fractions do you always have to multiply the denominator all the time or just certain problems?
• But my Math teacher told me to NEVER multiply the denominator
(1 vote)
• Sorry, but when you are multiplying fractions, you must multiply the denominators.

Maybe you are confusing multiplication with addition/subtraction. When adding/subtracting fractions once we have a common denominator, we never add/subtract the denominators. We only add/subtract the numerators.

hope this helps.
• The central hotel just hired a new chef . This chef mkes a hot sauce dat uses 1 3/4 tablespoons of chilly powder he needs to increase d recipe by 3 1/2 times how many table spoons of chilly powder should be used?
(1 vote)
• You should just multiply the tablespoons the chef uses by the number of times he needs to increase: 1 3/4 x 3 1/2. The answer is 4 3/8.
(1 vote)
• what fraction of an houyr is 7 minutes?
(1 vote)
• how do you know whether you have to add, subtract, divide, or multiply?? Someone help please asap!!
• In worded problems like this, the clue to add, subtract, divide, or multiply comes from a few words in the problem itself

If you see the words sum, altogether or increase in a worded problem, you probably have to do addition. If you see the words difference, decrease or less than, you probably have to do subtraction. If you see the words of, each or product, you probably have to multiply. If you see the words per, average or shared equally, you probably have to divide.

In this worded problem, we see the word "of". This means we have to multiply 1/2 by 3/4. If you do that, the answer is 3/8