Consumer Reports uses a 100-point customer satisfaction score to rate the nation's major chain stores. Assume that from past experience with the satisfaction rating score, a population standard deviation of ? = 13 is expected. In 2012, Costco, with its 432 warehouses in 40 states, was the only chain store to earn an outstanding rating for overall quality. A sample of 15 Costco customer satisfaction scores follows. 95 90 83 75 95 98 80 83 82 93 86 80 94 64 62 (a) What is the sample mean customer satisfaction score for Costco? (b) What is the sample variance? (Round your answer to two decimal places.) (c) What is the sample standard deviation? (Round your answer to two decimal places.) (d) Construct a hypothesis test to determine whether the population standard deviation of ? = 13 should be rejected for Costco. With a 0.05 level of significance, what is your conclusion? State the null and alternative hypotheses. H0: ?2 ≤ 169 Ha: ?2 > 169 H0: ?2 < 169 Ha: ?2 ≥ 169 H0: ?2 ≥ 169 Ha: ?2 < 169 H0: ?2 = 169 Ha: ?2 ≠ 169 H0: ?2 > 169 Ha: ?2 ≤ 169 Find the value of the test statistic. (Round your answer to three decimal places.) Find the p-value. (Round your answer to four decimal places.) p-value = State your conclusion. Do not reject H0. We cannot conclude that the population standard deviation is not 13.Reject H0. We cannot conclude that the population standard deviation is not 13. Do not reject H0. We can conclude that the population standard deviation is not 13.Reject H0. We can conclude that the population standard deviation is not 13.
Continuous Probability Distributions
Probability distributions are of two types, which are continuous probability distributions and discrete probability distributions. A continuous probability distribution contains an infinite number of values. For example, if time is infinite: you could count from 0 to a trillion seconds, billion seconds, so on indefinitely. A discrete probability distribution consists of only a countable set of possible values.
Normal Distribution
Suppose we had to design a bathroom weighing scale, how would we decide what should be the range of the weighing machine? Would we take the highest recorded human weight in history and use that as the upper limit for our weighing scale? This may not be a great idea as the sensitivity of the scale would get reduced if the range is too large. At the same time, if we keep the upper limit too low, it may not be usable for a large percentage of the population!
95 | 90 | 83 | 75 | 95 |
98 | 80 | 83 | 82 | 93 |
86 | 80 | 94 | 64 | 62 |
Trending now
This is a popular solution!
Step by step
Solved in 4 steps