The population standard deviation for the age of GPTC students is15 years. If we want to be 95% confident that the sample mean age is within two years of the true population mean age of GPTC students, how many randomly selected GPTC students must be surveyed? Round your answer UP to the next higher interger to ensure that the sample sizi large enough.

The Chancellor wants you to calculate the sample size needed with a margin of error of 15, 99% confidence, and a population standard deviation of 22.

Humerus bones from the same species of animal have approximately the same length-to-width ratios. It is known that Species A has a mean ratio of 5.9. Suppose that 100 fossil humerus bones were unearthed at a site where Species A is known to have flourished. (We assume that all bones are from the same species.) The length-to-width ratios of these bones have a sample mean 5.6 and sample standard deviation 0.25.   Can we conclude that the mean ratio of these bones is significantly smaller than those of Species A? Test with a 0.01 significance level.   What is the standard error?

The ages of the employees at Solar Systems, Inc. is normally distributed with a mean of 32.7 years and a standard deviation of 1.8 years. What percentage of employees at Solar Systems, Inc. are younger than 30 years old? Round your answer to the nearest tenth of a percent.