Scientific Measurement Target Practice 3
Chemistry I
Accuracy, Precision, and Error
The potato chip filler is set to put 16 oz. of chips in each bag. The Quality Control supervisor at the processing
facility has obtained a random sample of five bags from each of five days.
Bag 1
Bag 2
Bag 3
Bag 4
Bag 5
Precision
Accuracy
Percent Error
Monday
14.2
14.8
14.5
14.6
15.1
Moderate
Moderate
2.4%
Potato Chips per Bag (ounces)
Tuesday
Wednesday
14.2
16.0
17.9
16.0
16.0
16.1
16.2
16.0
16.8
15.9
Low
High
Moderate
High
8.13%
0%
Thursday
16.5
16.7
16.5
16.8
16.6
High
Moderate
10.8%
Friday
15.5
15.5
15.5
15.5
15.5
Very High
Moderate
3.125%
1. Describe the accuracy and precision for each of these ovens qualitatively. Calculate the percent error for
each. Add this information to the data table.
2. The actual mass of a sample is 45.0 g. The researcher measured the mass to be 46.2 g. What was the percent
error in this measurement?
2.67%
3. The actual mass of a sample is 0.25 g. The researcher measured the mass to be 0.29 g. What was the percent
error in this measurement?
16%
4. The actual length of a sample is 10 cm. The researcher obtains a 5% error. What two lengths could the
researcher have obtained when they measured the sample?
9.5 cm, 10.5 cm
5. The actual volume of a sample is 54.6 mL. The researcher obtains a 2.88% error. What two volumes could
the researcher have obtained when they measured the sample?
56.173 mL, 53.028 mL
6. The actual density of a sample is 75 g/mL, The researcher obtains a 0.2% error. What two densities could
the research have obtained when the measured the sample?
74.85 g/mL, 75.15 g/mL
Significant Figures in Measurements
7. Tell how many significant figures each of these numbers has.
a. 7402.0 5
b. 84.1
3
e. 0.0000506
c. 90.57040
7
8. Round each of these numbers to four significant figures.
a. 421.684453 421.7
b. 6.2016
c. 85.00
6.202
85.00
9. Round each of these numbers to two significant figures
a. 872,145,325,698,213 870,000,000,000,000
b. 0.215
c. 0.00154
d. 8,000,000.05
0.22
0.0015
f.
0.84
d. 9
9
3
2
9
e. 0.00154876321
f.
74.000
d. 9.058
9.1
e. 5.269
5.3
f. 0.0021
0.001549
74.00
0.0021
Significant Figures in Calculations
10. Add the following values. Use appropriate significant figures. 4.5 g, 9.658 g, 10.457 g, 0.021 g.
24.6 g
11. Add the following values. Use appropriate significant figures. 124.9 g, 124.975 g, 124.95487 g.
374.6 g
12. Subtract 16.2 mL from 32.548 mL. Use appropriate significant figures.
16.4 mL
13. Subtract 1650.0 g from 2187.65 g. Use appropriate significant figures.
5637.7 g
14. Multiply 17.4 cm by 5.23 cm by 14.587 cm. Use appropriate significant figures.
1330 cm3
15. Multiply 0.0025 nm by 0.1249 nm. Use appropriate significant figures.
0.00031 nm
16. Divide 15.487 by 2.34. Use appropriate significant figures.
6.62
17. Divide 2.1 by 0.354. Use appropriate significant figures.
5.9