Puzzling Percent: Word Problems!

Lesson Plan - Get It!

Audio:

Percentages are not just something for a math quiz — they are EVERYWHERE around you!

In this lesson, you will have a chance to look at word problems that have a percentage in them. You may be asked to find part of a number, a percent itself, or what the whole entire number is.

Let's start by reviewing how to tackle straightforward percent problems.

• Do you remember what the two methods for solving percentage problems?

See if you can describe the process for each.

• Did you mention that you can find a percentage by using an equation or by using proportions?

If so, you are absolutely correct! Chances are you prefer one way over the other, and that is okay. It is good, however, to be familiar with both ways.

Watch this Percentage word problem 2 video by Math Meeting for a quick example using the equation method:

Hopefully, you were reminded about two important words to remember when solving percent problems using equations:

Now, let's use a proportion to solve the same problem from the video. But first, let's remind ourselves of what a proportion is.

Proportion: Statement where two ratios (or fractions) are equal to each other

• 35% of what number is 14?

Give it a try and come back to check your answer.

Remember:

Part (Is) / Whole (Of) = % number / 100

Answer:

14/x = 35/100 ← First, substitute x for the number for which we are trying to solve.

From here, you will cross multiply. Take the 14 • (times) 100 and set that = (equal to) x • (times) 35:

14(100) = 35x

1400/35 = 35x/35 ← Divide both sides by 35 as a final step to get x alone.

40 = x ← This means that 14 is 35% of the number 40

Fantastic! Now you should be confident and ready to try some word problems.

The steps used to solve word problems are exactly the same as those shown above, but be careful — word problems can be tricky, especially when trying to determine which number is the whole, the part, and the percent.

Word problems can also contain unnecessary information just to throw you off track, so make sure you pay attention to all the details!

Watch this Percent word problem example 2 | Decimals | Pre-Algebra | Khan Academy video to see a word problem solved correctly:

In this problem, it was fairly straightforward that you needed to find the percentage, and the other two numbers would be substituted in for the part and the whole.

Honestly, deciding what gets substituted where is the trickiest part. If you can handle that, then solving becomes easy!

Let's look at one more problem together, where you need to find the whole (total) number:

Looking for the whole (total number)

Watch Percent word problem example 3 | Ratios, rates, and percentages | 6th grade | Khan Academy to see an example where you are solving for the whole (total) number.

If you feel like you are ready to solve the problem independently, hit "pause" as soon as you see the question. Solve the problem and then click "play."

If you don't feel ready, that is OK. Watch each step and take notes in your math notebook!

Once you have watched the videos, you can move to the Got It? section to try a few practice problems on your own.