Grade 7 · Math

7th grade Estimate how many: tag, catch again and compare worksheet

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Estimate how many: tag, catch again and compare

Grade 7 Math Worksheet

NameDate

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

Ari tags 50 ladybugs in a garden. Later, 40 are caught and 8 have tags. About how many are there in all?
Bo marks 60 beans and mixes them into a big jar. A scoop of 48 beans has 12 marked ones. About how many are there in all?
Esme puts stickers on 30 turtles' shells. Later, 50 turtles are spotted and 5 have stickers (they look very proud). About how many are there in all?
4.
Jun tagged 50 ladybugs; a later catch of 40 had 8 tagged. Which proportion finds the total N?
- 8/40 = 50/N
- 40/8 = 50/N
- 8/50 = N/40
5.
Kira marked 60 beans; a scoop of 48 had 12 marked. Which proportion finds the jar's total N?
- 48/12 = 60/N
- 12/48 = 60/N
- 12/60 = 48/N
6.
In Luz's ratio table, which row goes with the whole garden?
- 8 tagged, 40 in all
- 50 tagged, N in all
- 40 tagged, 50 in all
7.
Milo's second catch has fewer tagged butterflies than expected. What does that suggest about the meadow?
- Fewer butterflies than thought
- No butterflies of any kind
- More butterflies than thought
8.
Ren adds 100 colored grains to a rice bag, mixes, and scoops 100 grains: 20 are colored. About how many grains are in the bag?
- About 2,000
- About 120
- About 500
9.
Tala marks 30 marbles in a bag, mixes, and draws 20: 4 are marked. About how many marbles are in the bag?
- About 24
- About 150
- About 54
10.
Why can Zee's bean-jar method also estimate fish in a lake?
- Beans and fish weigh the same
- Both use a marked share
- Both are counted one by one

Estimate how many: tag, catch again and compare. Every version has 10 questions, and the answer key prints on the second page.

I can write the tagged share of a second catch as a fraction.
I can set up tagged ÷ total in the catch = tagged ÷ total in the whole group and solve it with a ratio table.
I can find how many were never tagged by taking the tagged ones away from the estimate.
I can explain why the answer is an estimate and what makes it less trustworthy (poor mixing, lost tags, new births).

Standard: 7.SP.A.2 (partial), 7.RP.A.3 (partial)

population: The whole group being counted, like every butterfly in a meadow

sample: The smaller group actually caught or counted

tag: A harmless mark, sticker or dot that shows an animal or object was counted before

proportion: Two equal ratios

estimate: A careful guess based on numbers

Your child put the catch size on top. The fraction tagged is tagged ones ÷ all the ones caught.

Your child's proportion was upside down. Tagged in the catch is to the catch as tagged in all is to the whole population.

Your child gave the whole population. The question asks for the untagged ones, so subtract the tagged ones.

What is the most common mistake with estimate how many: tag, catch again and compare?

Your child put the catch size on top. The fraction tagged is tagged ones ÷ all the ones caught.

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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