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9) A vendor offers various t-shirts for sale on an Intemet commerce site. Some o

ID: 3375508 • Letter: 9

Question

9) A vendor offers various t-shirts for sale on an Intemet commerce site. Some of his t-shirts sell quite well, others have yet to find an interested customer. The summary statistics are listed on right, based on the number of sales per month for each of 80 different t-shirt designs. fedian lin 15 Max sd 7.84 a. What is the shape of this distribution? Explain how you know b. If the vendor spends $2 per t-shirt in shipping costs, what is his average monthly costs per t-shirt sold? What is the standard deviation of this cost? Show work. c. As time passes, the vendor has simplified his profit calculation. He estimates that he has monthly flat costs of $35, with a gain of $3.50 per t-shirt sold. What is the median of his profit? The IQR? d. What are the mean and standard deviation of his profit? e. What is more appropriate in this case using mean and standard deviation, or using median and IQR?

Explanation / Answer

mean

23

median

15

min

0

Q1

3

Q3

21

max

82

sd

7.84

Galton skewness =(Q1+Q3?2Q2)/(Q3?Q1)

So skewness is =(3+21-30)/(21-3)=-1/3

So the distribution is negatively skewed

mean

23

median

15

min

0

Q1

3

Q3

21

max

82

sd

7.84