DURHAM UNIVERSITY — Department of Mathematical Sciences
COLLECTION 2010
DAMS and Statistics
MATH1711 and MATH1541
Name:
College:
Time allowed: 45 minutes. Answer all questions in the space provided.
Approved electronic calculators may
be used.
1. Data was collected to study how the time taken to refill a softdrink vending machines relates to the number
of cases required to fill the machine and the distance from the delivery truck to the machine. The results
of a sample of 25 refills can be summarised as follows:
Variable
Mean
Standard deviation
Distance (feet)
331
·
8
180
·
3
Number of cases
8
·
2
5
·
4
Time (minutes)
29
·
0
15
·
9
The regression equation for predicting refill time from distance and number of cases was found to be:
Predicted time = 2
.
3 + 0
.
0124
×
Distance + 2
.
7
×
Cases
Give an assessment of the relative importance of the distance and the number of cases for making predictions
of refill time.
2. The following data are the heights (in inches) of 6 married couples:
Wife
66
64
66
65
70
65
Husband
72
68
70
68
71
65
The mean height of the wives is 66 inches and the standard deviation is 2.1 inches. The mean height of the
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 Spring '11
 DrU.Picchini
 Statistics, Standard Deviation

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