1.What sample size is needed to estimate a population mean within

60

of the true mean value using a confidence level of

95%,

if the true population variance is known to be

122,500?

The sample size must be at least

enter your response here.

(Round up to the nearest whole number.)

2.A random sample of

500

items reveals that

280

of the items have the attribute of interest.

a. What is the point estimate for the population proportion for all items having this attribute?

b. Use the information from the random sample to develop a

90%

confidence interval estimate for the population proportion, p, of all items having this attribute of interest.

a. The point estimate is

enter your response here.

(Round to two decimal places as needed.)

b. The confidence interval estimate is

enter your response here------enter your response here.

(Round to three decimal places as needed. Use ascending order.)