# Question

How large a random sample is required from a population whose standard deviation is 4.2 so that the sample estimate of the mean will have an error of at most 0.5 with a probability of 0.99?

## Answer to relevant Questions

If x is a value of a random variable having an exponential distribution, find k so that the interval from 0 to kx is a (1 – α) 100% confidence interval for the parameter θ. For large n, the sampling distribution of S is some-times approximated with a normal distribution having the mean σ and the variance σ2/2n (see Exercise 8.28 on page 250). Show that this approximation leads to the ...Use the modification suggested in Exercise 11.26 to rework Exercise 11.21, given that there are 900 sixth graders in the school district. Twelve randomly selected mature citrus trees of one variety have a mean height of 13.8 feet with a standard deviation of 1.2 feet, and 15 randomly selected mature citrus trees of another variety have a mean height of 12.9 ...Use the result of Exercise 11.13 to rework Exercise 11.45, given that the poll has reason to believe that the true proportion does not exceed 0.30.Post your question

0