The buyer for an electronics store wants to estimate the propertion of defective

Question

The buyer for an electronics store wants to estimate the propertion of defective wireless game controllers in a shipment of 5,000 controllers from the store's primary supplier. The shipmeat consists of 200 boxes each containing 25 controllers. The buyer numbers the boxes from 1 to 200 and randomly selects six numbers in that range. She then opens the six boxes with the corresponding numbers, examines all 25 controllers in each of these boxes, and determines the proportion of the 150 controllers that are defective. What type of sample is this? (A) Biased random sample (B) Nonrandom sample (C) Simple random sample (D) Stratified random sample (E) Cluster random sample A program that was intended to cure a penson's fear of spiders was offered at a local zoo. Volunteers with a fear of spiders participated in the program, which included bolding a spider for 15 minutes. One month after they completed the program, the participants were contacted and surveyed about the program.Over 90 percent of the participants claimed they were cured of their fear of spiders. Based on the description of the program, which of the following statements is true? (A) Because over 90% of the participants claimed to be cured, the results prove that holding spider will cure a person's fear of spiders (B) Because over 90% of the participants claimed to be cured, the routs can be generalized to the population of all people who have a fear of spiders. Because the participants were volunteers, the study is a census of all people in the local area who have a fear of spiders. (D) Because the participants were self-selected,a person's desire to be cured could be a confounding variable. (E) Because participants held a spider for 15 minutes, the stady is an experiment and the results can be gencralized to the population of all poople who have a fear of spiders 9. An agricultural scientist wanted to compare the effect of a new fertilizer to that of three older fertilizers-X Y and 2-on the growth of vegetables typically grown in small gardens.Two hundred grcen bean seedlings were individually planted in identical pots and randomly assigned to one of four groups of 50 each. Seedlings in one were given the new fertilizer, and the three remaining groups of seedlings were given fertilizers X, Y, or Z, respectively. At the end of four wecks, all scodlings were dried and weighed. The scientist found that the mean weight of the sodlings in the group given the new fertilizer was significantly prateran the mean weights of seedlings in the other three groups. The scieatist concluded that the new ferilizer was more effective than the other fertilizers for all vegetables. Why is the scientist's conclusion pot appropriate? (A) The study was observational, so cause and effect cannot be concluded (B) The study was observational, so no replication was used in the study (C) The experiment only included green beans, so the results not be generalized to all vegetables. (D) The experiment did not group the seedlings into blocks by the variety of beans (E) The experiment lacked a control group that did not use any fertilizer.

Explanation / Answer

Q 7 Answer: E) Cluster Random Sampling, because first researcher randomly selects 6 boxes ( named as clusters) and then examine each and every unit( all 25 controllers) of each cluster(box) .

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