Six percent of computer chips produced by Cheapo Chips are defective. Each month a random sample of 200 chips manufactured that month are taken. Let X = the number of defective chips in the sample. To reduce the percentage of defective chips, the company contracts with a new supplier for some important components. In the next month, the sample of 200 chips has only 8 defective ones. Can the company conclude that the new components have reduced the rate of defective chips produced? Explain:

The response rate of a survey is the proportion of all people who were selected but did not complete the survey.    True  False

ixd s 67 Dr 5. Find the percentage of data points that lie above z 1.03. Draw a picture to support your work.

Las Vegas has seen increased competition from Singapore and Macau for customers in the casino resort industry. One measurement of success is the average length of stay by visitors. The data in this file show the number of days a random sample of visitors stayed at each location. a. Using α = 0.05 to determine if there is a difference in the average length of stay by visitors for the three locations. Follow the steps as outlined in the exercises. b. If warranted, perform a multiple comparison test to determine which pairs are different using α = 0.05. c. Verify your results using Excel.

Utilizing the previous table: A sample of 25 cities have been classified as high or low on their homicide rates and the number of handguns sold within the city limits. How would you classify the strength of the relationship?

How hard is it to reach a businessperson by phone? If p is the proportion of of calls. How many business phone calls should you include in a random sample to be 90% the point estimate will be within 0.02 from p? Business people can becreached by a single phone call approximately 18% of the time.

Arsenic is toxic to humans and people can be exposed to it through contaminated drinking water, food, dust, and soil. Scientists have devised a non-invasive way to measure a person's level of arsenic poisoning: by examining toenail clippings. In a recent study, scientists measure the level of arsenic (in mg/kg) in toenail clippings of 8 people who lived near a former arsenic mine in Great Britain. The following levels are recorded. 0.8, 1.9, 2.7, 3.4, 3.9, 7.1, 11.9, 26.0 Below are the summary statistics of the data. min Q1 median Q3 max sd n mean 0.8 2.5 3.65 8.3 26 7.2125 8.368041 8 Suppose the 8 people examined were randomly sampled from residents near the former arsenic mine. Is it legitimate to construct a 95% confidence interval for the mean level of arsenic (in mg/kg) in toenail clippings for residents near the former arsenic mine using a t-distribution? Explain briefly.

The pathogen Phytophthora capsici causes bell peppers to wilt and die. Because belI peppers are an important commercial crop, this disease has undergone a great deal of agricultural research. It is thought that too much water aids the spread of the pathogen. Two fields are under study. The first step in the research project is to compare the mean soil water content for the two fields. Units are percentage of water by volume of soil. Field A samples, x: 10.0 10.7 15.5 10.4 9.9 10.0 16.6 15.1 15.2 13.8 14.1 11.4 11.5 11.0 Field B samples, x,: 8.3 8.5 8.4 7.3 8.0 7.1 13.9 12.2 13.4 11.3 12.6 12.6 12.7 12.4 11.3 12.5 A USE SALT Use a calculator to calculate x,, s,,x,, and s,. (Round your answers to four decimal places.) x, (a) Assuming the distribution of soil water content in each field is mound-shaped and symmetric, use a 5% level of significance to test the claim that field A has, on average, a higher soil water content than field B. (1) What is the level of significance?

Healthy Eating  Americans appear to be eating healthier. Between 1970 and 2013 the per capita consumption of broccoli increased 1200.5% from 0.5 to 6.4 pounds. A nutritionist followed a group of people randomly assigned to one of three groups and noted their monthly broccoli intake (in pounds). At a=0.05 is there a difference in means? Group A           Group B         Group C 2.0                      2.0                  3.7 1.5                       1.5                   2.5  0.75                    4.0                  4.0 1.0                       3.0                  5.1 1.3                        2.5                  3.8  3.0                       2.0                  2.9 Null Hypothesis Alternative Hypothesis Find the Critical Value Find the Variance of each sample F= Make the decision Summarize Show how to use the TI-84 and Excel to work out the problems.

The chlorine added to swimming pools to combat relatively short shelf before it loses its effectiveness. Records indicate that the mean shelf life of a 5 gallon jug of chlorine is 2,160 hours (90 days). As an experiment, Holdlonger was added to the chlorine to whether it would increase the shelf life of the chlorine. A sample of nine jugs of chlorine had these shelve lives (in hours): 2,159, 2, 170, 2,180, 2,179, 2,160, 2,167, 2,171, 2,181 and 2,185. At the .025 significance level, has Holdlonger increased the shelf life of the chlorine? S=9.3823, sample mean=2172.44 STATE THE NULL AND ALTERNATE HYPOTHESIS. Determine the critical value for the decision rule.