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Course: Algebra 1>Unit 3

Lesson 3: Word problems with multiple units

Working with units: FAQ

Why is it important to be able to convert rates?

Often, we want to compare two rates that are expressed in different units. We need to convert one of the rates to match the other one in order to make a meaningful comparison.
Practice with our Rate conversion exercise.

How do we go about choosing appropriate quantities for modeling?

It depends on the problem we're trying to solve. We'll want to choose quantities that are relevant to the problem and that we're able to measure directly or indirectly. For example, if we're trying to model the speed of a car, we might want to use distance and time as our quantities.

How can we use formulas and units to solve problems?

By using formulas that relate different quantities to each other, we can use known values to solve for unknown values. Units are important because they remind us what the quantities represent and help us to check our work.
Practice with our Formulas and units exercise.

What are some real-world applications of these topics?

There are countless examples! Engineers use rate conversions in order to design systems that operate at different speeds or frequencies. Scientists use formulas and units to solve problems ranging from calculating the densities of substances to measuring the rates of chemical reactions. And of course, people in all sorts of professions use these skills to make everyday calculations, such as converting measurements for a recipe or determining how long it will take to drive somewhere based on the speed limit.

Want to join the conversation?

• Y'all! Am I the only one who is still having trouble with this? It's making my brain hurt.
• You're definitely not the only one lol
• This stuff hard
• you'll figure it out
• Express 160 pounds (lbs) in kilograms (kg). Round your final answer 2 decimal places.

Units of Length Units of Weight Units of Capacity
1 in. = 2.54 cm 1 oz ≈ 28.35 g 1 L ≈ 1.06 qt
1 m ≈ 3.28 ft 1lb ≈454 g 1 gal ≈ 3.79 L
1 m ≈ 1.09 yd 1 kg ≈ 2.2 lb
1 mi ≈ 1. 61 km
• is this important?
(1 vote)
• Yes, this is very important for many different careers.

•you need to know drug conversion if your going to be a doctor or paramedic.

•if you want to be a chemist you'll need to be able to convert between different chemical measurements.

• if your trading currency you have to be able to convert between currencies.

While most of these can be done via computer, it can still be a very useful skill to have. Hope this helps!
• This topic is hard.
• Soon it will get easier
(1 vote)
• How this can work in real life
• It could be helpful when using a recipe for cooking or following a blueprint that uses different units to measure in
• This unit is making me rethink whether I should be an engineer : /
• What happens if the quantity for modeling is not appropiate?
• When will I use this in day-to-day life, besides in the work field, I will most likely not join.
(1 vote)
• You will use it everyday. Like for example, when you spend money or play games or other stuff like that.
• For everyone in the comments having trouble with units, I just want to say that it took me lots of brainpower to go through the exercises too. It can be difficult! However here are some tips that may help you all when going through these exercises:

1. Try to understand what the units mean. If, let's say, dollars per kilogram (\$/kg) seems abstract to you while you are working on a problem, this makes understanding and solving the problem harder! 5\$/kg for example just means that a single kilogram holds value/costs 5 dollars. This implies that if we have 2 kilograms, the cost will be 10 dollars, etc. Understanding what the units mean and what they are trying to tell you is paramount.

2. Be thourough. Read the problem multiple times. Write down the important stuff and make sure you get the units right! Be it trip per month, dollars per worker, kilograms per square meter, etc. Organize relevant information, that will help.

3. As roxie.mcleod mentioned already in the questions section, talk to yourself and try to explain the problem to yourself. Talk and explain to yourself while you go through the problem and you are trying to solve it. This piece of advice helped me a lot personally and helped me get 100% on the exercise.

4. Practice, practice, practice. I know you may be really bored because of this constantly repeated piece of advice, but really, you hear it so much because it works so well. Don't give up! Do a few problems, take a break every once in a while, the goal isn't to speedrun the unit really, it is to acquire knowledge.

If anyone has any additional advice you are welcome to share in the replies, I would love to hear it.