Question

11. A random sample of 22 observations is used to estimate the
population mean. The sample mean and the sample standard deviation
are calculated as 135.5 and 30.50, respectively. Assume that the
population is normally distributed. **[You may find it useful
to reference the** t table**.]**

**a.** Construct the 90% confidence interval for the
population mean.

**(Round intermediate calculations to at least 4 decimal
places. Round " t" value to 3 decimal places and final
answers to 2 decimal places.)**

Confidence Interval | ? (124.80 WRONG) |
to | ? (146.20 WRONG) |

**b.** Construct the 99% confidence interval for
the population mean.

**(Round intermediate calculations to at least 4 decimal
places. Round " t" value to 3 decimal places and final
answers to 2 decimal places.)**

Confidence Interval | ? (118.75 WRONG) |
to | ? (152.25 WRONG) |

**c.** Use your answers to discuss the impact of
the confidence level on the width of the interval.

1. As the confidence level increases, the interval becomes wider.

2. As the confidence level increases, the interval becomes narrower.

Please do not answer if you are not sure, THANk YOU! :)

Answer #1

The statistical software output for this problem is:

Hence,

a) 90% confidence interval:

124.31 to 146.69

b) 99% confidence interval:

117.09 to 153.91

c) As the confidence level increases, the interval becomes wider.

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