# Question: A manufacturer has been purchasing raw materials from a supplier

A manufacturer has been purchasing raw materials from a supplier whose consignments have a variance of 15.4 (in squared pounds) in impurity levels. A rival supplier claims that she can supply consignments of this raw material with the same mean impurity level but with lower variance. For a random sample of 25 consignments from the second supplier, the variance in impurity levels was found to be 12.2. What is the probability of observing a value this low or lower for the sample variance if, in fact, the true population variance is 15.4? Assume that the population distribution is normal.

## Answer to relevant Questions

What is meant by the statement that the sample mean has a sampling distribution? The lifetimes of a certain electronic component are known to be normally distributed with a mean of 1,600 hours and a standard deviation of 400 hours. a. For a random sample of 16 components, find the probability that the ...Scores on a particular test, taken by a large group of students, follow a normal distribution with a standard deviation of 40 points. A random sample of 16 scores was taken to estimate the population mean score. Let the ...Another product packaged by Prairie Flower Cereal, Inc., is an apple-cinnamon cereal. To test the packaging process of 40-ounce (1,134-gram) packages of this cereal, 23 samples of six packages each are randomly sampled and ...Assume a normal distribution with known population variance. Calculate the LCL and UCL for each of the following. a. x-bar = 50; n = 64; σ = 40; α = 0.05 b. x-bar = 85; n = 225; σ2 = 400; α = 0.01 c. x-bar = 510; n = ...Post your question