1. You want to obtain a sample to estimate a population proportion. Based on previous evidence, you believe the population proportion is approximately p*=14%. You would like to be 98% confident that your estimate is within 2% of the true population proportion.

How large of a sample size is required if you use the previous evidence for the population proportion? n =

How large of a sample size is required if you do not use the previous evidence for the population proportion? n =

2. As Director of Student Services for the Lawrence County School District, you wish to estimate the proportion of families with school-aged children who would enroll in a before-school tutoring program if such a program were available. A random sample of 41 families was polled and it was found that 18 would enroll in such a program.

a. Let p represent the proportion of all families in the district who would enroll in the before-school tutoring program. Find a point estimate for p. (Round result to 3 decimal places.)

Find a 90% confidence interval for p . (Round results to 3 decimal places.) ? < ? < ?

The Lawrence County School Board president tasks you with doing a larger study, to develop a more precise estimate. The director would like an estimate for the proportion of families who would use the before school tutoring program that is within 3% of the population percentage, with 90% confidence. Using the original study (described above) as a preliminary estimate for the population proportion , what is the minimum sample size required to fulfill the board president's request?

Minimum sample size: n =

3. Out of 500 people sampled, 115 had kids. Based on this, construct a 99% confidence interval for the true population proportion of people with kids. Give your answers as decimals, to three places ? < p < ?

4. You measure 49 randomly selected textbooks' weights, and find they have a mean weight of 53 ounces. Assume the population standard deviation is 9.2 ounces. Based on this, construct a 90% confidence interval for the true population mean textbook weight. Give your answers as decimals, to two places ? < u < ?

5. In a survey, 13 people were asked how much they spent on their child's last birthday gift. The results were roughly bell-shaped with a mean of $48 and standard deviation of $8. Construct a confidence interval at a 95% confidence level.

Use StatCrunch

Use the format: Point estimate Margin of Error. Give your answer to one decimal places. ? ?