Statistics Questions and Answers

At a local restaurant, the amount of time that customers have to wait for their food is normally distributed with a mean of 12 minutes and a standard deviation of 2 minutes. Using the empirical rule, determine the interval of minutes that the middle 99.7% of customers have to wait.

When Alexa commutes to work, the amount of time it takes her to arrive is normally distributed with a mean of 34 minutes and a standard deviation of 3.5 minutes. What percentage of her commutes will be longer than 35 minutes, to the nearest tenth?

What is the purpose of finding a sample mean or sample proportion? The only way to get a good estimate of the population mean or proportion is to take small sample sizes and create a sampling distribution. There is no purpose because you should always find the population mean or proportion. Estimates are not accurate. The purpose is to estimate the population mean or proportion. The purpose is to show what one part of the population mean or proportion looks like.

Suppose that pulse rates among healthy adults are normally distributed with a mean of 79 beats/minute and a standard deviation of 8 beats/ minute. What proportion of healthy adults have pulse rates that are at most 84 beats/ minute? Round your answer to at least four decimal places.

Many college graduates who are employed full-time have longer than 40-hour work weeks. Suppose that we wish to estimate the mean number of hours, µ,worked per week by college graduates employed full-time. We'll choose a random sample of college graduates employed full-time and use the mean of thissample to estimate μ. Assuming that the standard deviation of the number of hours worked by college graduates is 6.30 hours per week, what is the minimumsample size needed in order for us to be 95% confident that our estimate is within 1.5 hours per week of µ? Carry your intermediate computations to at least three decimal places. Write your answer as a whole number (and make sure that it is the minimum wholenumber that satisfies the requirements). (If necessary, consult a list of formulas.)

The weights (in pounds) of 19 preschool children are 23, 49, 25, 43, 34, 48, 37, 30, 29, 47, 24, 27, 22, 45, 46, 42, 26, 50, 20 Find 25th and 80th percentiles for these weights. (If necessary, consult a list of formulas.) (a)The 25th percentile: pounds (b)The 80th percentile: pounds

A coin-operated coffee machine made by BIG Corporation was designed to discharge a mean of eight ounces of coffee per cup. If it dispenses more than that onaverage, the corporation may lose money, and if it dispenses less, the customers may complain. BIG Corporation would like to estimate the mean amount of coffee, μ, dispensed per cup by this machine. BIG will choose a random sample of cup amountsdispensed by this machine and use this sample to estimate μ. Assuming that the standard deviation of cup amounts dispensed by this machine is 0.43 ounces,what is the minimum sample size needed in order for BIG to be 90% confident that its estimate is within 0.07 ounces of μ? Carry your intermediate computations to at least three decimal places. Write your answer as a whole number (and make sure that it is the minimum wholenumber that satisfies the requirements). (If necessary, consult a list of formulas.)