Answer to Question #325174 in Statistics and Probability for Lynn

Question

C. Solve the following problems.

1. Suppose observation on 50 circuits yields a sample mean of 65 ohms with standard deviation of 6 ohms. Determine the 99% confidence intervals of the mean resistance.

2. What sample size would we need for a 90 percent confidence interval that has a margin of error of 6 and a population standard deviation of 23?

3. A random selection of 40 entering college students has the following GPAs.

4.0 3.5 3.0 3.3 3.8 3.1 3.6 4.0

3.2 3.0 3.5 3.2 3.0 3.2 4.0 3.0

3.0 2.8 5.6 3.0 3.2 3.5 3.2 2.8

3.2 2.9 3.0 2.8 4.0 3.7 3.0 3.3

3. 9 3.5

3.4 3.0

3.3 3.1

3.2 2.8

Construct a 90% confidence interval around the mean.

4. The mean scores of a random sample of 15 students who took a special test is 80. if the standard deviation of the scores 4. and the sample comes from an approximately normal population, find the interval estimate of the population mean adopting a confidence level of 95%.