Self-Check 8.1
- Page ID
- 36498
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Self-Check 8.1
- Suppose we have data from a sample. The sample mean is 15, and the error bound for the mean is 3.2. What is the confidence interval estimate for the population mean?
- Suppose average pizza delivery times are normally distributed with an unknown population mean and a population standard deviation of six minutes. A random sample of 28 pizza delivery restaurants is taken and has a sample mean delivery time of 36 minutes.
Find a 90% confidence interval estimate for the population mean delivery time. Write an interpretation.
- How many adults must be randomly selected to estimate the mean FICO (credit rating) score of working adults in the United States? We want 95% confidence that the sample mean is within 3 points of the population mean, and the population standard deviation is 68.
1
Self-Check 8.1
- The table below shows a different random sampling of 20 cell phone models. Use this data to calculate a 93% confidence interval for the true mean SAR for cell phones certified for use in the United States. As previously, assume that the population standard deviation is σ= 0.337. And write an interpretation.
|
Phone Model |
SAR |
|
Blackberry Pearl |
1.48 |
|
HTC Evo Design 4G |
0.8 |
|
HTC Freestyle |
1.15 |
|
LG Ally |
1.36 |
|
LG Fathom |
0.77 |
|
LG Optimus Vu |
0.462 |
|
Motorola Cliq XT |
1.36 |
|
Motorola Droid Pro |
1.39 |
|
Motorola Droid Razr M |
1.3 |
|
Nokia 7705 Twist |
0.7 |
|
Nokia E71x |
1.53 |
|
Nokia N75 |
0.68 |
|
Nokia N79 |
1.4 |
|
Sagmen Puma |
1.24 |
|
Samsung Fascinate |
0.57 |
|
Samsung Infuse 4G |
0.2 |
|
Samsung Nextus S |
0.51 |
|
Samsung Replenish |
0.3 |
|
Sony W518a Walkman |
0.73 |
|
ZTE C79 |
0.869 |
- Find the critical value, Z/2 corresponding to a 92% confidence level.