# Math 104/Math 104 Midterm (Answer 100%) - 93913

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1. A 99% confidence interval estimate can be interpreted to mean that

a. if all possible samples are taken and confidence interval estimates are developed, 99% of them would include the true population mean somewhere within their interval.
b. we have 99% confidence that we have selected a sample whose interval does include the population mean.
c. Both of the above.
d. None of the above.

2. Which of the following is not true about the Student's t distribution?
a. It has more area in the tails and less in the center than does the normal distribution.
b. It is used to construct confidence intervals for the population mean when the population standard deviation is known.
c. It is bell shaped and symmetrical.
d. As the number of degrees of freedom increases, the t distribution approaches the normal distribution.

3. A confidence interval was used to estimate the proportion of statistics students that are females. A random sample of 72 statistics students generated the following 90% confidence interval: (0.438, 0.642). Based on the interval above, is the population proportion of females equal to 0.60?
a. No, and we are 90% sure of it.
b. No. The proportion is 54.17%.
c. Maybe. 0.60 is a believable value of the population proportion based on the information above.
d. Yes, and we are 90% sure of it.

4. A confidence interval was used to estimate the proportion of statistics students that are female. A random sample of 72 statistics students generated the following 90% confidence interval: (0.438, 0.642). Using the information above, what size sample would be necessary if we wanted to estimate the true proportion to within 0.08 using 95% confidence?
a. 105
b. 150
c. 420

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