Chemistry 420
Problem set #1
Due at the beginning of class September 15
No late assignments will be accepted.
No name, no grade.
Show all of your work for each answer. Partial credit will be given and NO credit will be awarded if no
work is shown. Be careful to use correct significant figures.
1.
(10 points) Last season, University of Illinois running back Rashard Mendenhall had rushing
efforts of: 33, 139, 150, 214, 76, 160, 67, 85, 189, 201, 88, 124, and 155 yards. Calculate the
mean and standard deviation of Mendenhall’s yards per game performance.
(2 pts for setting up mean, 2 pts for correct mean value, 3 pts for setting up SD, 2 pts for
correct SD, 1 pt for reasonable significant figures)
1
33 139 150
214
76 160
67
85 189
201 88 124 155
129
13
N
i
i
x
x
N
=
++++
++
+
+++
==
=
∑
()
(
)
(
)
(
)
(
)
(
)
2
222 2
22
2
222
1
33 129
139 129
150 129
214 129
76 129
160 129
67 129
85 129
189 129
201 129
88 129
124 129
155 129
1
12
N
i
i
xx
s
N
=
−
−+−+−+−+
−+−+
−+
−+−+−+
−+−+−
−
∑
9216 100
441 7225
2809
961 3844 1936
3600
5184 1681
25
676
37698
56
12
12
s
+
+
+
+
+
+
+
=
Mendenhall’s average yards per game =
129 ± 56
Acceptable answers= 129 ± 56, 130 ± 60, 129 ± 56.0
2.
(10 points, Skoog 1
‐
10) The data in the table below were obtained during a colorimetric
determination of glucose in blood serum.
Glucose concentration (mM)
Absorbance, A
0.0
0.0002
2.0
0.150
4.0
0.294
6.0
0.434
8.0
0.570
10.0
0.704
a.
Assuming a linear relationship, find the least
‐
squares estimates of the slope and
intercept.
(4 points; 1 point for Excel plot or worksheet, 1.5 pts for each value)
b.
Use Excel to find the standard deviations of the slope and intercepts. What is the
standard error of the estimate?
(2 points)
c.
Determine the 95% confidence intervals for the slope and intercept.
d.
A serum sample gave an absorbance of 0.350. Find the glucose concentration and its
standard deviation.
(4 pts: 2 pts for setting up equation, 0.5 pts for reasonable error
propagation, 0.5 pts for significant figures, 1 pt for final value)