The Friends of the Psychics network charges $3 per minute to learn the secrets that can turn your life around. The network charges for whole minutes only and rounds up to benefi t the company. Thus, a 2 minute 10 second call costs $9. Below is a list of 15 randomly selected charges.
| 3 | 9 | 15 | 21 | 42 | 30 | 6 | 9 | 6 | 15 | 21 | 24 | 32 | 9 | 12 |
- Find the mean of the sample.
- Find a point estimate of the variance of the population.
- Can this sample be used to estimate the average length of a call? If so, what is your estimate? If not, what can we estimate using this sample?
In a sample of 400 textile workers, 184 expressed extreme dissatisfaction regarding a prospective plan to modify working conditions. Because this dissatisfaction was strong enough to allow management to interpret plan reaction as being highly negative, they were curious about the proportion of total workers harboring this sentiment. Give a point estimate of this proportion
Electric Pizza was considering national distribution of its regionally successful product and was compiling pro forma sales data. The average monthly sales figures (in thousands of dollars) from its 30 current distributors are listed. Treating them as (a) a sample and (b) a population, compute the standard deviation.
| 7.3 | 5.8 | 4.5 | 8.5 | 5.2 | 4.1 |
| 2.8 | 3.8 | 6.5 | 3.4 | 9.8 | 6.5 |
| 6.7 | 7.7 | 5.8 | 6.8 | 8.0 | 3.9 |
| 6.9 | 3.7 | 6.6 | 7.5 | 8.7 | 6.9 |
| 2.1 | 5.0 | 7.5 | 5.8 | 6.4 | 5.2 |
The National Bank of Lincoln is trying to determine the number of tellers available during the lunch rush on Fridays. The bank has collected data on the number of people who entered the bank during the last 3 months on Friday from 11 A.M. to 1 P.M. Using the data below, find point estimates of the mean and standard deviation of the population from which the sample was drawn.
| 242 | 275 | 289 | 306 | 242 | 385 | 279 | 245 | 269 | 305 | 294 | 328 |
Joe Jackson, a meteorologist for local television station WDUL, would like to report the average rainfall for today on this evening's newscast.
| 8.8 | 14.0 | 21.3 | 7.9 | 12.5 | 20.6 | 16.3 | 14.1 | 13.0 |
The Greensboro Coliseum is considering expanding its searing capacity and needs to know both the average number of people who attend events there and the variability in this number. The following are the attendances (in thousands) at nine randomly selected sporting events. Find point estimates of the mean and the variance of the population from which the sample was drawn.
| 8.8 | 14.0 | 21.3 | 7.9 | 12.5 | 20.6 | 16.3 | 14.1 | 13.0 |
Test 9