Statistics (Gray)
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In-class Exercises, Class 2
Name: _________________________
1) How many significant figures in each of the following numbers?
- 82.059
- 0.0003
- 200300
- 300.0
2) Write the numbers above in scientific notation maintaining the same number of significant figures.
3) To how many significant figures should each answer be rounded?
- 40.5 / 1020.2 = 0.039698
- 0.002 kg + 98.3 kg = 98.3002 kg
- 1001 cm – 20.86 cm = 980.14 cm
4) Calculate the answer to the correct number of significant figures.
- 102.259 =?
- What is the pH if the [H+] = 7.245 x 10-6 M
In-class Exercises, Class 3
Name: _________________________
1) Find the absolute and percent relative uncertainty and express each answer with the correct number of significant figures.
- 9.23 (±0.03) + 4.21 (±0.02) – 3.26 (±0.06) = ?
- 91.3 (±1.0) * 40.3 (±0.2) / 21.1 (±0.2) = ?
- [6.2 (±0.2) – 4.2 (±0.1)] / 9.43 (±0.05) =?
2) Why is the data reported below incorrect? Report the data correctly.
5.4359 M ± 0.00671 M
In-class Exercises, Class 4
Name: _________________________
1) For the following data set, calculate the 99% confidence interval.
Sample |
Value |
---|---|
1 |
3.0541 |
2 |
2.9845 |
3 |
3.0512 |
4 |
2.99584 |
2) A standard reference material is certified to contain 94.6 ppm of an organic contaminant in soil. Your analysis gives values of 98.6, 98.4, 97.2, 94.6 and 96.2 (ˉx = 97.0, s = 1.655). Do your results differ from the expected result at the 95% confidence level? If you made one more measurement at 94.5, would your conclusion change (new ˉx = 96.583, s = 1.798)?
In-class Exercises, Class 5 and 6
Name: _________________________
1) Given the following data, are the precisions of the two datasets significantly different at the 95% confidence level? What is the tcalc for these two means? Are the two means significantly different at the 95% confidence level?
ˉX1 = 80.34 s=0.0548 N=4
ˉX2 = 80.46 s=0.2793 N=5
2) Using both the Grubbs and the Q-test, can the last data point be excluded at the 95% CI?
Data |
---|
0.1503 |
0.1505 |
0.1496 |
0.1493 |
0.1496 |
0.1497 |
0.1507 |
0.1617 |
ˉx = 0.1514
s = 0.004181
In-class Exercises, Class 7
Name: _________________________
1) Match the formula below to the statistical method.
Methods:
- Mean
- Standard deviation
- Variance
- Confidence intervals
- Relative standard deviation
- t-test, case 1
- t-test, case 2; variances are equal
- t-test, case 2; variances are not equal
- compare 2 variances
- reject an outlier
Degrees of freedom=(s21/n1+s22/n2)2(s21/n1)2n1−1+(s22/n2)2n2−1 |
|
spooled=√s21(n1−1)+s22(n2−1)n1+n2−2 |
s=√∑Ni=1(Xi−ˉX)2N−1 |
=100×sˉx |
=s2 |
μ=ˉx±ts√N |
|μ−ˉx|>ts√N |
tcal=ˉx1−ˉx2spooled√n1n2n1+n2 |
tcalculated=|ˉx1−ˉx2|√s21/n1+s22/n2 |
ˉX=∑Ni=1XiN |
Q=gaprange |
Fcal=s21s22 |
Gcalc=|questionablevalue−ˉx|s |
Contributors and Attributions
- Sarah Gray, Stockton University (sarah.gray@stockton.edu)
- Sourced from the Analytical Sciences Digital Library