Economics 2122A/B Study Guide - Midterm Guide: Simple Random Sample, Systematic Sampling, Statistical Inference

1. The sample variance of a random sample of 50 observations from a normal population was found to be s² = 80. Can we infer at the 1% significance level (i.e., a = .01) that the population variance is less than 100 (i.e., x < 100) ?
2. Repeat part a changing the sample size to 100.

A simple random sample of 60 items resulted in a sample mean of 67. The population standard deviation is 16.

a. Compute the 95% confidence interval for the population mean (to 1 decimal).

b. Assume that the same sample mean was obtained from a sample of 120 items. Provide a 95% confidence interval for the population mean (to 2 decimals).