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Chapter 9: Q. 9.15 (page 358)

Cadmium, a heavy metal, is toxic to animals. Mushrooms, however are able to absorb and accumulate cadmium at high concentrations. The Czech and Slovak governments have set a safety limit for cadmium in dry vegetables at \(0.5\) part per million M. Melgar et al. measured the cadmium levels in a random sample of the edible mushroom Boletus pinicola and published the results in the paper "Influence of Some Factors in Toxicity and Accumulation of Cd from Edible Wild Macrofungi in NW Spain. A hypothesis test is to be performed to decide whether the mean cadmium level in Boletus pinicola mushrooms is greater than the government's recommended limit.

a. determine the null hypothesis

b. determine the alternative hypothesis

c. classify the hypothesis test as two tailed, left tailed or right tailed.

Short Answer

Expert verified

Part a. \(H_{0}:\mu =0.5\) ppm

Part b. \(H_{0}:\mu >0.5\) ppm

Part c. The hypothesis is a right tailed test.

Step by step solution

01

Part a. Step 1. Explanation

Here the null hypothesis is the mean of cadmium level in Boletus pinicola mushrooms equal to \(0.5\) ppm.

\(H_{0}:\mu =0.5\) ppm

02

Part b. Step 1. Explanation

Here the alternative hypothesis is the mean of cadmium level in Boletus pinicola mushrooms greater to \(0.5\) ppm.

\(H_{0}:\mu >0.5\) ppm

03

Part c. Step 1. 

As the alternative hypothesis is preferred that is mean of cadmium level in Boletus pinicola mushrooms greater to \(0.5\) ppm so, this is right tailed test.

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Most popular questions from this chapter

Cheese Consumption. Refer to Problem 24. The following table provides last year's cheese consumption: in pounds, 35 randomly selected Americans.

4629333842403433323628472642363245243928334433263727313637373622443629

  1. At the 10%significance level, do the data provide sufficient evidence to conclude that last year's mean cheese consumption for all Americans has increased over the 2010 mean? Assume that 蟽=6.9lb. Use a z-test. (Note: The sum of the data is 1218lb.)
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The following graph portrays the decision criterion for a onemean z-test, using the critical-value approach to hypothesis testing. The curve in the graph is the normal curve for the test statistic under the assumption that the null hypothesis is true.

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a. rejection region.

b. nonrejection region.

c. critical value(s).

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e. Draw a graph that depicts the answers that you obtained in parts (a)-(d).

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b. At the 5%significance level, do the data provide sufficient evidence to conclude that last year's mean local monthly bill for cell phone users decreased from the 2009 mean of \)48.16?Assume that the population standard deviation of last year's local monthly bills for cell phone users is $25.
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