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## Pre-algebra

# Solving unit price problem

CCSS.Math:

Nierria earns $75 for 4 hours of tutoring. How much does Nierria earn per hour of tutoring? Created by Sal Khan and Monterey Institute for Technology and Education.

## Want to join the conversation?

- how can i express 1 mile in 4 min???(1 vote)
- 0.25 miles per minute(126 votes)

- Is there any video that explains and defines what Rates are? If not, can someone help me and define it?(3 votes)
- A rate is like a ratio.(14 votes)

- I am still confused on ratios and units? what should i do?(4 votes)
- HI! this lesson might get confused but here is a brief explanation.

A unit rate is a ratio between two different units with a denominator of one. When we divide a fraction's numerator by its denominator, the result is a value in decimal form. For example: 8/4 = 2 and 3/6 = 0.5. When we write numbers in decimal form, we can write them as a ratio with one as the denominator.

For example, we can write 2 as 2/1, and 0.5 as 0.5/1. However, since that approach can be a little clumsy, we usually drop the one. That said, it's important to remember the one is there, especially when working with unit rates.

For instance, 8 miles/4 hours = 2 miles/hour. Notice again that, while we did not include the 1, we did include the unit 'hour' Miles per hour is a familiar expression, as are unit rates such as:

interest/amount invested

revolutions/minute

salary/year

Hope this helps!(13 votes)

- Jacqueline spends 20% of her money on sweets and 32% on fares. if she spent $8 on sweets what is. (1) the amount of money she has left (2) The amount of money spent on fares (3) The amount she has left. I need help with this problem I am working on finding percentages using the unitary method on a calculator. But no matter what I do, I can't figure out the answers to this problem. what am I doing wrong?(5 votes)
- Set up a proportion using the information for sweets: 8/n = 20/100

Cross multiply: 20n = 800

Divide by 20: n = $40

This means Jacqueline started with $40

You can find the amount spent on fares by doing: x/40 = 32/100

Cross multiply: 100x = 1280

Divide by 100: x = $12.80

So, she spent $12.80 on fares

To find amount left, do: 40 - 8 - 12.80

Hope this helps.(10 votes)

- Thank you for the help! You are so kind.(6 votes)
- who else used a calculator for this?(8 votes)
- At1:58, the company should charge for area not number of offices because it could be huge and another one is small and both are then same price.(7 votes)
- Yes, but it is a fictional company for one's education, not a real situation.(1 vote)

- Reduce the following rates to their unit rate forms. Write the numerator of each unit rate in the box provided.

$40 per 8 Hours(4 votes)- You need to find dollars per hour.

Divide: 40/8 to find you answer.(6 votes)

- Yes, the 0 is called an extraneous (not needed) digit, but they are the same thing.(3 votes)

- What is an easyer way to divide(3 votes)

## Video transcript

- [Instructor] We're told
that Nierria earns $75 for 4 hours of tutoring. How much does Nierria earn
for 1 hour of tutoring? Pause this video, and see
if you can figure that out. Well, the key here is $75
for 4 hours of tutoring. And there's a couple of
ways you can think about it. The ratio here is $75 for every 4 hours. So if you wanted one hour of tutoring, well, it's just going
to be 1/4 of the $75, or you could just take 75 and divide by 4. Another way you could think about it, you could say Nierria gets $75 for every 4 hours, which is another way of saying that Nierria is going to earn 75 divided by 4 dollars per hour. So really we just have to figure out what 75 divided by 4 is. So let's do a little bit of long division. So 4 goes into 7 one time, 1 times 4 is 4. We're going to subtract. 7 minus 4 is 3. Bring down that 5. 4 goes into 35 eight times. 8 times 4 is 32. I will subtract again. I get a 3. Well now I'm going to
get some decimals here, so let me bring down a zero. 4 goes into 30 seven times. 7 times 4 is 28. Subtract, and then I get a
2. Bring down another zero. 4 goes into 20 five times. 5 times 4 is 20, and I am done, no more remainder here. So we get that Nierria
earns 18.75 dollars, dollars per hour, or you can just say that
she makes $18.75 per hour.