Ratios

Today's Goal: Today I will be able to express ratios as fractions in simplest form (Lowest terms) and explain the meaning of a ratio as a solution to a word problem.

What is a ratio: A comparison of two numbers by division. They can be written: 2 out of 3; 2 to 3; 2:3 or as a fraction 2/3. The numbers compared may be said to be in the same family. For example, cats and dogs are both animals. Drums and flutes are both instruments.

Remember that a ratio can be treated as a fraction. If we have 25 M&M's and 10 of them are red, we can write the ratio 10 out of 25. We then reduce it to simplest form just like a fraction. Either divide by the greatest common factor or do the Lola May method. Our M&M example is written 2 out of 5 as we divided both numbers by their greatest common factor, which is 5.

Video

Practice Sites

Ratio Blaster - Find equal ratios and blast them with your laser. Don't let them land!!!

Ratio Rumble - Find ratios that match the required recipe.

Math Games site - Are the given ratios equivalent?

Explain:

This ratio can then be explained as: Two out of five berries is a strawberry.

Another example:

Fred asked his classmates how many had cell phones. 21 student said they had cell phones. He then asked how many of these were iPhones. 7 student said they had iPhones. Find the ratio of iPhones to cell phones and express it is lowest terms. Then explain its meaning.

The ratio is 7:21 that is 7 iPhones to 21 cell phone. We then reduce the ratio to lowest terms by dividing by the greatest common factor of 7. Our ratio in lowest terms is 1:3. The explanation for this ratio is: One out of every three cell phones is a iPhone.

Report abuse