Accuracy, precision and percent error

Answer Key - Grade 10 Science Worksheet - Building Confidence

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

1. 1.

   A class measures the density of water as 1.02 g/cm³. The accepted value is 0.99802 g/cm³ (USGS, 21 °C). What is the percent error, to 0.01%, Ari?

   2.2 %
2. 2.

   A class measures the density of sugar as 1.55 g/cm³. The accepted value is 1.5805 g/cm³ (CRC Handbook). What is the percent error, to 0.01%, Bo?

   1.93 %
3. 3.

   A class measures the density of table salt as 2.25 g/cm³. The accepted value is 2.17 g/cm³ (CRC Handbook). What is the percent error, to 0.01%, Esme?

   3.69 %
5. 4.

   On the card, how would you describe target B, Kira?

   • Accurate, not precise
   • Accurate and precise
   • Precise, not accurate
6. 5.

   On the card, why isn't target C precise, Luz?

   Use the picture in question 4.

   • Its dots are spread widely
   • It has too few dots
   • Its dots miss the center
7. 6.

   What does accuracy describe, Milo?

   • How many trials were done
   • Closeness to the accepted value
   • Closeness of results to each other
8. 7.

   A balance gives 5.01, 5.02 and 5.01 g for the same sugar cube. What does this show, Pia?

   • The cube is changing mass
   • The readings are precise
   • The balance is broken
9. 8.

   Where does an accepted value come from, Ren?

   • The class's first trial
   • A guess before the lab
   • A trusted reference, like the CRC Handbook
10. 9.

    What does percent error measure, Tala?

    • How long the lab took
    • How far a result is from accepted
    • How close the trials are to each other
11. 10.

    Why does percent error use the absolute value of the difference, Zee?

    • So it is a size, not a direction
    • So the units cancel
    • So the final answer comes out bigger