Download presentation

1
**How do I solve a proportion?**

Proportions How do I solve a proportion?

2
**Proportions – What are they??**

Proportions are a way to relate information. They compare two ratios.

3
**Proportions – What are they??**

Proportion = a pair of equal ratios ×3 ×3

4
**How do we tell if something really is a proportion?**

Method 1: Put both sides in lowest terms. ÷5 ÷15 ÷5 ÷15

5
**How do we tell if something really is a proportion?**

Method 1: Put both sides in lowest terms. The fractions are the same, so it is a true proportion.

6
**How do we tell if something really is a proportion?**

Method 2: Find the cross products.

7
Cross-Product Multiply the numerator of one ratios by the denominator of the other ratio. 3×2=6 6×1=6

8
**The cross products are the same, so it is a true proportion.**

If the cross products are equal, the then ratios are equal, and it is a true proportion. 3×2=6 The cross products are the same, so it is a true proportion. 6×1=6

9
**Are these proportions equal?**

Method 1 – Lowest Terms ÷2 ÷2

10
**Are these proportions equal?**

Method 1 – Lowest Terms No – they are not equal!!

11
**Are these proportions equal?**

Method 2 – Cross Products 8×16=128 9×14=126 No – they are not equal!!

12
**Are these proportions equal?**

YES – they are equal!!

13
**Are these proportions equal?**

YES – they are equal!!

14
**Are these proportions equal?**

No – they are not equal!!

15
**Now, let’s try something harder**

Sometimes, we will only know 3 of the 4 values in a proportion. The missing value is a VARIABLE. Take a look…. Z is the variable

16
**Now, let’s try something harder**

When we have a variable, we can still cross-multiply. 10×5 = 50 1×Z = 1Z

17
**Now, let’s try something harder**

What do you think we are going to do now? 10×5 = 50 1×Z = 1Z Write the cross products equal to each other.

18
**Now, let’s try something harder**

What do you think we are going to do now? 50 = 1Z Write the cross products equal to each other.

19
**Now, let’s try something harder**

What do you think we are going to do next? 50 = 1Z It is an equation so we are going to do the inverse - DIVIDE.

20
**Now, let’s try something harder**

What do you think we are going to do next? 50 = 1Z 50 ÷ Z = 50 so Z = 50 It is an equation so we are going to do the inverse - DIVIDE.

21
**Solve for the variable:**

Let’s try again Solve for the variable: 8×15 = 120 4×X = 4X 4X = 120 120÷4=30 so X = 30

22
**Here are some steps: 1.) Cross multiply.**

2.) Write the cross-products equal to each other. 3.) Divide the number by itself by the number with the variable. 4.) Write your answer as x = …

23
Now You TRY

24
**How do I solve a proportion?**

Summarize Answer the EQ: How do I solve a proportion?

Similar presentations

© 2024 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google