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Statistical Techniques in Business & Economics by Lind

EXERCISES FROM LIND (Statistical Techniques in Business & Economics by Lind, et al)

1. The Grand Strand Family Medical Center is specifically set up to treat minor medical emergencies for visitors to the Myrtle Beach area. There are two facilities, one in the Little River Area and the other in Murrells Inlet. The Quality Assurance Department wishes to compare the mean waiting time for patients at the two locations. Samples of the waiting times, reported in minutes, follow:

Location Waiting Time
Little River 31.73 28.77 29.53 22.08 29.47 18.60 32.94 25.18 29.82 26.49
Murrells Inlet 22.93 23.92 26.92 27.20 26.44 25.62 30.61 29.44 23.09 23.10 26.69 22.31
At the .05 significance level, is there a difference in the mean waiting time?

3. A consumer buying cooperative tested the effective heating area of 20 different electric space heaters with different wattages. Here are the results.
Heater Wattage Area
1 1,500 205
2 750 70
3 1,500 199
4 1,250 151
5 1,250 181
6 1,250 217
7 1,000 94
8 2,000 298
9 1,000 135
10 1,500 211
11 1,250 116
12 500 72
13 500 82
14 1,500 206
15 2,000 245
16 1,500 219
17 750 63
18 1,500 200
19 1,250 151
20 500 44
a. Compute the correlation between the wattage and heating area. Is there a direct or an indirect relationship?
b. Conduct a test of hypothesis to determine if it is reasonable that the coefficient is greater than zero. Use the .05 significance level.
c. Develop the regression equation for effective heating based on wattage.
d. Which heater looks like the "best buy" based on the size of the residual?

3. The Banner Mattress and Furniture Company wishes to study the number of credit applications received per day for the last 300 days. The information is stated below:

Number of Credit Frequency
Applications (Number of Days)
0 50
1 77
2 81
3 48
4 31
5 or more 13

To interpret, there were 50 days on which no credit applications were received, 77 days on which only one application was received, and so on. Would it be reasonable to conclude that the population distribution is Poisson with a mean of 2.0? Use the .05 significance level. Hint: To find the expected frequencies use the Poisson distribution with a mean of 2.0. Find the probability of exactly one success given a Poisson distribution with a mean of 2.0. Multiply this probability by 300 to find the expected frequency for the number of days in which there was exactly one application. Determine the expected frequency for the other days in a similar manner.

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