Ratio and proportion

What’s a ratio?

A ratio shows the relative size of two values

Let’s say you planted bushes to grow berries

• You planted 5 rows of raspberry bushes and 4 rows of blackberry bushes.
• You have a 5:4 ratio

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If I took one berry from each bush, it would look like this, a 5:4 ratio

If I took two berries from each bush, it would look like this, a 10:8 ratio

If you didn’t know, now you know

An equation stating that two ratios are equal is called a proportion.

Proportion

You probably are not going to just pick 5 or 10 berries

If you didn’t know, now you know

Farmers, carpenters, engineers, bakers – many, many careers use ratios and proportions.

So do people just working around their house or yard.

Let’s write an equation

Bottle–fed lambs drink a formula made of 2 cups milk replacer for 5 cups of warm water.

Let’s write an equation

Let’s put this into words

Milk replacer, when you pour it out, looks like this.

My little cousin hiding behind the bushes bet me $10 he could solve this problem faster than you.

To ‘solve an equation’ means to find the value that makes the equation true.

If you didn’t know, now you know

Proportions are just equivalent fractions

Something you already know

• If you multiply the numerator and denominator of a fraction by the same number, you get equivalent fractions

Solve this equation

I can multiply 2 x 3 to get 6.�So, I can multiply 5 x 3 to get 15

Let’s test it.

• Here is a pitcher. It holds 8 cups.
• I put 2 cups of milk replacer in and then 5 cups of water.

Let’s test it.

• I put 2 cups of milk replacer in

Let’s test it.

• Then 5 cups of water.

There is a 2:5 ratio

• 2 cups of milk replacer to
• 5 cups of water

If I have 6 cups of milk replacer, I’ll need 15 cups of water

You can count it up and see for yourself

Let’s write and solve another equation

Let’s write and solve another equation

How I solved it …

Both lamb’s weight and milk are measured in ounces

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The new lamb, Mary, weighs 130 ounces. How many ounces should she drink each day?

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Both lamb’s weight and milk are measured in ounces

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The new lamb, Mary, weighs 130 ounces. How many ounces should she drink each day?

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She should drink 1/5 of her weight.

To find out how much she should drink, divide 130 by 5

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She should drink 26 ounces per day.

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Terri has harvested 16,000 pounds of blackberries

Terri has harvested 16,000 blackberries