Estimate how many: tag, catch again and compare

Answer Key - Grade 7 Math Worksheet - Challenge Me

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

1. 1.

   Ari tags 40 butterflies; a later catch of 30 has 6 tagged. About how many have no tag?

   160
2. 2.

   Bo marks 25 beans in a jar; a scoop of 60 has 5 marked. About how many have no tag?

   275
3. 3.

   Esme stickers 80 snails in a garden (no snail minded); a later count of 50 snails finds 10 with stickers. About how many have no tag?

   320
4. 4.

   Jun's two later catches give estimates of 200 and 250 butterflies. Which is the best single estimate?

   • Exactly 200
   • About 225
   • About 450
5. 5.

   Kira tagged 40. Catch A: 6 of 30 tagged. Catch B: 4 of 40 tagged. Which catch gives the bigger estimate?

   • They give the same
   • Catch A: about 200
   • Catch B: about 400
6. 6.

   Why might Luz do the second catch several times?

   • To tag each one of the butterflies
   • Averaging gives a steadier estimate
   • To make the numbers smaller
7. 7.

   Noah says the jar holds 48 beans because the scoop held 48. Agree or disagree?

   • Agree: the scoop counts the whole jar
   • Disagree: scale up with the ratio
   • Agree: 48 is close to 60
8. 8.

   Pia says the tag-and-catch method gives the exact number of turtles. Agree or disagree?

   • Agree: proportions are exact
   • Disagree: it is an estimate
   • Agree: turtles stay put
9. 9.

   Tala's tagged butterflies stay near one bush and don't mix. What could go wrong?

   • Nothing changes
   • The catch's tagged share is off
   • The tags stop working
10. 10.

    Many new snails hatch between Zee's two counts. Why is that a problem?

    • New ones change the mix
    • The ratio gets exact
    • Snails lose their stickers