Essay on Qnt 561

2218 Words Jun 5th, 2011 9 Pages
Chapter 3; 80, 82, 87

80. Creek Ratz is a very popular restaurant located along the coast of northern Florida. They serve a variety of steak and seafood dinners. During the summer beach season, they do not take reservations or accept “call ahead” seating. Management of the restaurant is concerned with the time a patron must wait before being seated for dinner. Listed below is the wait time, in minutes, for the 25 tables seated last Saturday night.

|28 |39 |23 |67 |37 |28 |56 |40 |28 |50 |
|51 |45 |44 |65 |61 |27 |24 |61 |34 |44 |
|64 |25 |24 |27 |29 | | | | | |

a. Explain why the times are a population.

These times
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(-51.2)(-51.2) = 2621.44

(-31.2)(-31.2) = 973.44

(-11.2)(-11.2) = 125.44

(8.8)(8.8) = 77.44

(28.8)(28.8) = 829.44

(48.8)(48.8) = 2381.44

I then multiply the totals by their respective frequency.

- 2621.44*3 = 7864.32

- 973.44*8 = 7787.52

- 125.44*12 = 1505.28

- 77.44*16 = 1239.04

- 829.44*7 = 5806.08

- 2381.44*4 = 9525.76

I then add the totals of the f(M-X)2 and divide that by the total frequency number minus 1.

7864.32+7787.52+1505.28+1239.04+5806.08+9525.76

= 33728/50-1

= 688.326 (Take the square root of this number)

= $26.24 is the standard deviation

c. Use the Empirical Rule to estimate the proportion of costs within two standard deviations of the mean. What are these limits?

- The mean for this example is $141.20 and the standard deviation for this example is $26.24. The Empirical Rule states that approximately 95% of all observations will be within plus and

QNT 561 – Week 1 Problem Set 6

minus two standard deviations of the mean. To find this, I take the mean and multiply it by the standard deviation and multiply that by 2.

- $141.20 +- ($26.24)(2)

= About 95% of the electricity costs are between $88.72 and $193.68

87. Refer to the Real Estate data, which reports information on homes sold in the Denver,

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