Grade 7 · Math

7th grade Percent increase, percent decrease and percent error worksheet

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Percent increase, percent decrease and percent error

Grade 7 Math Worksheet - Challenge Me

NameDate

Circle the best answer, or write your answer on the line.

Kira's school library now has 220 books, after the number of books grew by 10%. How many books did it have before?
Milo's bucket has 72 liters of water left after 25% leaked out. How many liters did the bucket hold before?
After 40% of the students went on a trip, 135 students are left at Noah's school. How many students were at the school before the trip?
Pia's band had 200 fans. The crowd grew by 20%, then shrank by 10%. How many fans are there at the end?
Ren's young tree is 60 centimeters tall. It grows by 50%, then a storm trims it by 20%. How tall is the tree at the end?
Zee's orchard had 400 apples. Picking day brought 10% more apples, then wind took 10% of all of them. How many apples are there at the end?
Esme's step counter is within 5% of the true count. The true count is 8000 steps. What is the largest count it could show?
Jun's stopwatch is within 3% of the true time. The true time is 60 seconds. What is the smallest time it could show?
9.
Kira's plant shop starts with x plants. The number of plants goes up by 20%, then down by 10%. Which expression gives the final number of plants?
- 1.08x
- 0.9x
- 1.2x
- 1.1x
10.
x is the number of pages Milo read on day one. The next days it goes up by 40%, then down by 30%. Which expression gives the final number of pages?
- 1.4x
- 0.7x
- 1.1x
- 0.98x

Percent change and percent error. Every version has 10 questions, and the answer key prints on the second page.

I can find the new amount after a percent increase or decrease, and the number I multiply by (1.05 for "5% more", 0.9 for "10% less").
I can find the percent a quantity went up or down, and the percent error of a guess or a reading, by comparing the change to the old (or actual) amount.
I can go back from a new amount to the old one, do two percent changes in a row, and find the largest and smallest readings a tool can show.

Standard: 7.RP.A.3, 7.EE.A.2

increase / decrease: Going up by a percent, or down by a percent, of the old amount.

the 100 row: The old (starting or true) amount. It is always 100%.

the change: How much the amount went up or down: new minus old, ignoring the sign.

multiplier: The number you multiply the old amount by to get the new amount, like 1.05.

percent error: How far a guess or reading is from the true amount, as a percent of the true amount.

Your child found the change (the percent of the old amount) and stopped.

Your child added the percent number itself to the amount, as if 25% meant 25 more.

Your child subtracted the percent number itself from the amount, as if 25% meant 25 less.

Ask: after a 10% increase, is the new amount more than the old amount or just the 10%?

Ask: is 25% of 40 equal to 25?

What is the most common mistake with percent increase, percent decrease and percent error?

Your child found the change (the percent of the old amount) and stopped.

How can I help my child with percent increase, percent decrease and percent error?

Ask: after a 10% increase, is the new amount more than the old amount or just the 10%?

Are these 7th grade math worksheets free to print?

Yes. All 6 printable versions at each level are free to print, with the answer key, and no account is needed.

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