Multiply And Divide Fractions

Multiplying Fractions:

Real life applications where common fractions are multiplied or divided include:

Steps to multiply fractions are:

The extra step to divide fractions is to multiply by the reciprocal of the second fraction (that is, turn the second fraction upside and then multiply).



Example One - Image Reduction

An image is reduced to one half of its original size. If the original measurement is 34 cm, what is the new reduced measurement?

Answer:
12 × 34
= 38 cm


Example Two - Adapting Recipes for Large Groups

A risotto recipe for 5 people uses 2 12 cups of rice. How many cups of rice are required to feed 20 people?

Answer:
Multiplier
= 20 ÷ 5
= 4

No. of cups of rice
= 2 12 × 4
= 10 cups

Questions

Q1. 13 × 25
Q2. 38 × 45
Q3. 2 14 × 3 23

Answers
A1. 215
A2. 310
A3. 8 14


Dividing Fractions:

Example Three - Gym Training

In a gym the whole 2 12 hour training session is divided into 14 hour parts. How many parts is this?

Answer:
2 12 ÷ 14
= 52 ÷ 14
= 52 × 41
= 202
= 10 parts

Questions

Q1. 67 ÷ 14
Q2. 38 ÷ 12
Q3. 2 45 ÷ 110

Answers
A1. 3 37
A2. 34
A3. 28