1. A machine cuts plastic into sheets that are 35 feet (420 inches) long. Assume that the population of lengths is normally distributed. Complete parts(a) and(b).

a. The company wants to estimate the mean length the machine is cutting the plastic within 0.25 inch. Determine the minimum sample size required to construct a 90% confidence interval for the population mean. Assume the population standard deviation is 0.50 inch. N=_____

b. Repeat part(a) using an error tolerance of 0.125 inch. N=_____

Which error tolerance requires a larger samplesize? Explain.:____________

2. In a survey of 3988 adults, 705 say they have seen a ghost. Construct a99% confidence interval for the population proportion. Interpret the results.

a. A99% confidence interval for the population proportion is: (___,___)

b. Interpret your results: ______