MG 620 Research and statistics for Managers July 30, 2014
Final Exam Instructions: Answer all questions
Part II : Problem
1. In a sample of size of 10, the sum of all values is 400. What is the sample mean
a. 20 c. 800
b. 560 d. None of the above
SHOW YOUR WORK!
2. The following are the durations in minutes of a sample of long-distance phone calls within the continental United States reported by one long-distance carrier
Table 1
Time (in minutes) Relative Frequency 0 but less than 5 0.37 5 but less than 10 0.22 10 but less than 15 0.15 15 but less than 20 0.10 20 but less than 25 0.07 25 but less than 30 0.07 30 or more 0.02
Referring to Table 1, what is the width of each class?
a. 1 minute c. 5 minutes
b. 2%
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ii) Interpret the meaning of the slope, b1
iii) Predict the mean value of Y for X = 3
7. If SSR = 66 and SST = 88, compute the coefficient of determination, r2, and interpret its meaning.
8. The Management at Ohio National Bank does not want its customers to wait in line for service for too long. The manager of a branch of this bank estimated that the customers currently have to wait an average of 8 minutes for service. Assume that the waiting times for all customers at this branch have a normal distribution with a mean of 8 minutes and a standard deviation of 2 minutes.
Find the probability that randomly selected customer will have to wait for less than 3 minutes?
Instructions: Show all steps:
1. Draw the normal curve and indicate the mean, standard deviation, and the X bar scale
2. Identify the area of interest (that is shade the area under the curve that you will compute the probability).
3. Covert the X bar values in Z scores
4. Look up the Z standardized table for the cumulative area(s).
5. Now, make your decision ( that a customer will wait for less than 3