Constructing a Confidence Interval when the Population σσ is Known Suppose scores on exams in statistics are normally distributed with an unknown population mean and a population standard deviation of 3 points. A random sample of 36 scores is taken and gives a sample mean of 68. Find a 95% confidence interval estimate for the population mean exam score by providing the following information.

Mathematics scores on the CBBC standardized exam are normally distributed with a population mean of 164 and a population standard deviation of 12. Ms. Norbury believes her two classes of a total of 48 students have a mathematics comprehension different than 164 and she decides to give her classes the exam. The mean on the exam was 161. Test to determine if her class' mathematics comprehension is different than 164 at the 0.05 level of significance. (Show all seven steps.)

Find the 95% confidence interval for the variance and standard deviation for the time it takes a state police inspector to check a truck for safety if a sample of 21 trucks has a standard deviation of 5.2 minutes. Assume the variable is normally distributed.

A new material will replace the old material only if there is significant evidence that the mean strength of the new material is more than 2 units higher than the mean strength of the old material.        Sample from new material:     mean  is  98.064   ,     SD  is   5.6     and sample size is 13 Sample from old material:       mean  is  95.282   ,     SD  is   5.8      and sample size is 78 We do not know population standard deviations. Consider the test           ?0:????−????=2H0:μnew−μold=2   vs.  ?0:????−????>2H0:μnew−μold>2  What is the p-value?       (Hint:  best to use software, or else the Desmos Calculator for the 2 sample T and Z test)  Give as a decimal between 0 and 1 accurate to at least 4 decimal places.

Part Variability is critical in the manufacturing of the ball bearings. Large variances in the size of the ball bearings cause bearing failure and rapid wear out. Production standards call for a maximum variance of .0001 when the bearing sizes are measured in inches. A sample of 15 bearings shows a sample standard deviation of .014. a. Compute the 90% confidence interval estimate of the variance of the ball bearings in the population. b. Use a= 0.10 to determine whether the sample indicates that the maximum acceptable variance is being exceeded. Use critical value approach. ( Note: You must state null and alternative hypotheses, compute the test statistic, Report the critical Value, and draw a conclusion.

A Two-Sample Hypothesis TestThe mean number of English courses taken in a two-year time period by male and female college students is believed to be about the same. An experiment is conducted and data are collected from 29 males and 16 females. The males took an average of three English courses with a standard deviation of 0.8. The females took an average of four English courses with a standard deviation of 1.0. Are the means statistically the same? (Assume a 5% level of significance.)Useful tools:Normal Distribution Calculatort-Distribution Calculator 1. Which of the following null and alternative hypotheses match this scenario? A---H0:Δμ=0H0:Δμ=0Ha:Δμ≠0Ha:Δμ≠0 B---H0:Δμ≠0H0:Δμ≠0Ha:Δμ=0Ha:Δμ=0 C---H0:Δμ=0H0:Δμ=0Ha:Δμ>0 2. Which type of test should be applied? A---The alternative hypothesis indicates a right-tailed test. B---The alternative hypothesis indicates a left-tailed test. C---The alternative hypothesis indicates a two-tailed test. 3. Which type of distribution should be…