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## Pre-algebra

### Course: Pre-algebra>Unit 3

Lesson 4: Ratio application

# Part to whole ratio word problem using tables

Discover how to solve ratio problems with a real-life example involving indoor and outdoor playtimes. Learn to use ratios to determine the number of indoor and outdoor playtimes in a class with a 2:3 ratio and 30 total playtimes. Created by Sal Khan.

## Want to join the conversation?

• Total Students is 65, On the Formula at the begin, should be ask for the sum of girls and boys (13) or not? •  Hi Annet. You need to find the sum to be able to find the ratio. Example:

The ratio of girls to boys in a school is (5:6). If there are 33 students, how many boys are there and girls are there?

1. 5 + 6 = 11
2. 6/11 = boy part of the school/total students
3. 11 x ? = 33, so 6 x ? = ? boys
4. 11 x 3 = 33, so 6 x 3 = ?
5. 6 x 3 = 18
6. 18 boys

Now the second part of the question:

7. 18 boys, 33 students, ? girls
8. 33 - 18 = ? girls
9. 15 girls

There are 18 boys and 15 girls.

Check:
10. 18 + 15 = 33 students
• where did the 13 come from in the problem? like how did he get 13? • what in the world? this isvery difficult can someone explain please:( • Sure, I can help you! The basic concept of part to whole ratios, is that instead of comparing data to another piece of data in the question, you're comparing to the total amount of data. I hope I'm explaining this clearly; it is a bit of a difficult thing to understand. I struggled at first, too. Here's an example:

There are 5 apples, 4 bananas, and 6 oranges. What is the ratio of apples to total fruit?

First, you would want to add the total amount of fruit together - 5 + 4 + 6 = 15. The total amount of fruit is 15.

Since there are 5 apples, the ratio of apples to total fruits would be 5 : 15, or you could simplify to 1 : 3 (divide both sides of the ratio by 5 to simplify).

To try to explain further, instead of comparing one part to another part - for example, apples to bananas - you are instead comparing one part to the whole - which would be apples to all fruit -.

Let's do another example. Say you had ten pairs of blue socks, fifteen pairs of red socks, five pairs of black socks, and nine pairs of purple socks. What is the ratio of black socks to all socks?

First, you would want to add the number of all your socks together, which would be 10 + 15 + 5 + 9, equaling 39. You have 39 total pairs of socks.

Next, you would want to know how many black socks you had - which we know, you have 5 pairs. And then you can do the ratio of black socks to all socks.

Therefore, the ratio of black socks to all socks is 5 : 39.

I know this isn't specific to this particular problem in this video, but I hope these examples help you know how to solve part to whole ratio problems.

Let me know if you'd like me to explain the problem Sal does in this video for you.

Hope this helped! :)
• DUDE. Where were you when I was in middle school?? and high school? and College? • How is his hand writing so nice when he is doing that on a computer im jeoulous • *jealous • I have a question... It doesn't have anything to do with the video itself, rather all videos. Once you watch a video once... How do you rewatch it? It isn't allowing me to... Thank you! • why cant you multiply 5 and 8 and get 40 subtract 65 and 40 and get 25?   