Question 8.156
wiisales
59. Wii Game Sales. The following table represents the number of units sold (in 1000s) in the United States for the week ending March 26, 2011, for a random sample of 8 Wii games.14 The normal probability plot is given.
| Game | Units (1000s) |
Game | Units (1000s) |
|---|---|---|---|
| Wii Sports Resort | 65 | Zumba Fitness | 56 |
| Super Mario All Stars |
40 | Wii Fit Plus | 36 |
| Just Dance 2 | 74 | Michael Jackson | 42 |
| New Super Mario Brothers |
16 | Lego Star Wars | 110 |
461
- Confirm that the normality condition is met.
- Construct and interpret a 95% confidence interval for the population mean number of units sold.
- Calculate and interpret the margin of error.
- How could we decrease the margin of error of our confidence interval without decreasing the confidence level?
8.2.59
(a) Acceptable normality (b) (31, 79). We are 95% confident that μ, the population mean number of Wii game units sold per week for all weeks, lies between 31 thousand units and 79 thousand units. (c) thousand units. We can estimate the population mean number of Wii game units sold per week for all weeks to within 24 thousand units with 95% confidence. (d) Decrease the confidence level or increase the sample size. Increase the sample size. The only way to have both high confidence and a tight interval is to boost the sample size.