In: Statistics and Probability
The Downtown Parking Authority of Tampa, Florida, reported the following information for a sample of 232 customers on the number of hours cars are parked and the amount they are charged.
| Number of Hours | Frequency | Amount Charged | |||
| 1 | 22 | $ | 2 | ||
| 2 | 38 | 6 | |||
| 3 | 50 | 8 | |||
| 4 | 45 | 12 | |||
| 5 | 20 | 14 | |||
| 6 | 16 | 16 | |||
| 7 | 5 | 18 | |||
| 8 | 36 | 22 | |||
| 232 | |||||
Click here for the Excel Data File
a-1. Convert the information on the number of hours parked to a probability distribution. (Round your answers to 3 decimal places.)
a-2. Is this a discrete or a continuous probability distribution?
Discrete
Continuous
b-1. Find the mean and the standard deviation of the number of hours parked. (Do not round the intermediate calculations. Round your final answers to 3 decimal places.)
b-2. How long is a typical customer parked? (Do not round the intermediate calculations. Round your final answer to 3 decimal places.)
Find the mean and the standard deviation of the amount charged. (Do not round the intermediate calculations. Round your final answers to 3 decimal places.)
(a- 1)
The information on the number of hours parked is converted to a probability distribution as follows:
| Number of hours (x) | Probability (p) |
| 1 | 22/232 = 0.095 |
| 2 | 38/232 = 0.164 |
| 3 | 50/232 = 0.216 |
| 4 | 45/232 = 0.194 |
| 5 | 20/232 = 0.086 |
| 6 | 16/232 = 0.069 |
| 7 | 5/232 = 0.022 |
| 8 | 36/232 = 0.154 |
(a - 2)
Discrete
(b - 1)
From the probability distribution, the following Table, calculated:
| Number of hours (x) | Probability (p) | p.x | p.x2 |
| 1 | 0.095 | 0.095 | 0.095 |
| 2 | 0.164 | 0.328 | 0.656 |
| 3 | 0.216 | 0.648 | 1.944 |
| 4 | 0.194 | 0.776 | 3.104 |
| 5 | 0.086 | 0.430 | 2.150 |
| 6 | 0.069 | 0.414 | 2.484 |
| 7 | 0.022 | 0.154 | 1.078 |
| 8 | 0.154 | 1.232 | 9.856 |
| Total | ![]() |
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(i)
the mean of the number of hours parked. =
(ii)
the standard deviation of the number of hours parked.
(b - 2)
The number of hours a typical customer parked =
(c)
n = 8

| x | (x -
) |
(x -
)2 |
| 2 | - 10.25 | 105.0625 |
| 6 | - 6.25 | 39.0625 |
| 8 | - 4.25 | 18.0625 |
| 12 | - 0.25 | 0.0625 |
| 14 | 1.75 | 3.0625 |
| 16 | 3.75 | 14.0625 |
| 18 | 5.75 | 33.0625 |
| 22 | 9.75 | 95.0625 |
| Total = | 307.5 |
Standard Deviation (s) is given by:

So, answer is:
the mean of the amount charged. : 12.250
the standard deviation of the amount charged. 6.628