The following times were recorded by the quarter-mile and mile runners of a university track team (times are in minutes).
| Quarter-Mile Times: | 0.91 | 0.97 | 1.02 | 0.94 | 1.01 |
| Mile Times: | 4.52 | 4.36 | 4.59 | 4.71 | 4.49 |
After viewing this sample of running times, one of the coaches commented that the quarter milers turned in the more consistent times. Use the standard deviation and the coefficient of variation to summarize the variability in the data.
| Quarter milers | |
| Standard deviation (to 4 decimals) | |
| Coefficient of variation (to 1 decimal), | |
| Milers | |
| Standard deviation (to 4 decimals) | |
| Coefficient of variation (to 1 decimal), | |
Does the use of the coefficient of variation indicate that the coach’s statement should be qualified?
(i) Yes, the coefficient shows that as a percentage of the mean the quarter milers' times show more variability.
(ii) No, the coefficient doesn't show that as a percentage of the mean the quarter milers' times show more variability.
The following times were recorded by the quarter-mile and mile runners of a university track team...
Use Table 8.1, a computer, or a calculator to answer the following. Suppose a candidate for public office is favored by only 47% of the voters. If a sample survey randomly selects 2,500 voters, the percentage in the sample who favor the candidate can be thought of as a measurement from a normal curve with a mean of 47% and a standard deviation of 1%. Based on this information, how often (as a %) would such a survey show that...