A Chinese cell-phone manufacturer exclusively uses robots in one of its factories. A random test run results in 23 defective assemblies out of 500. Does this data suggest that the true percentage of defectives is less than 5%? Use NATDRC.

The Elisa test for the human immunodeficiency virus (HIV) that causes AIDS has been used in the screening of blood donations. As with most medical diagnostics test, the ELISA test is not infallible. If a person actually carries HIV, experts estimate that this test gives a positive result 97.7% of the time (the number is called the sensitivity of the test. If a person does not carry HIV ELISA gives a negative result 92.6% of the time. Suppose that 0.5% of the public carries HIV.

The drug manufacturer claim that taking gemfibrozil is beneficial to reduce the chance of heart attacks. 2051 men took the medication, and a control group of 2030 men took a placebo. During the next five years, 56 men in the drug group and 84 men in the placebo group had heart attacks. We would like to compare the proportion of men who develop heart attacks between the drug group and the placebo group. What are the correct x1 and x2 values in order to calculate the pooled sample proportion? a) x1=2051, x2=2030 b) x1=2051, x2=84 c) x1=56, x2=2030 O d) x1=56, x2=84

A software company is interested in improving customer satisfaction rate from the 55% currently claimed.  The company sponsored a survey of 247 customers and found that 146 customers were satisfied. What is the test statistic z?

Two different blood pressure medicines are being compared to determine if the average reduction in blood pressure is the same for each medication. The goal of the study is to determine if the medications differ. Twenty men age 50-60 years old are selected for the study. Ten men are chosen at random to receive the first medication and the other 10 men receive the second medication. Each of the 20 men is monitored for one month to determine the change in blood pressure over that time. Minitab provides the 95% confidence interval for (mu1 - mu2) (2.63, 14.18) a. Interpret this 95% CI. b. What assumptions (be specific) are necessary to construct this CI?

According to the Pew research center 65% of US adults believe that the government should play a larger role in addressing climate change. A random sample (SRS) of 80 US adults found that 56 US adults believe that the government should play a larger role in addressing climate change. Does this indicate that population proportion of US adults who believe that the government should play a larger role in addressing climate change is MORE THAN 65%? Given: a= 0.05 level    1. List your oH and aH: (symbols and words)    2. State and Check the conditions for the test:    3. Use the information in question: Identify the hypotheses being tested: Find your SE and test statistic by hand:    4. Use the information in question: State your conclusion given 05.0 level, in a complete sentence, in the context of the problem.     5. Use the information in question. Find the 95% confidence interval by hand using: Given z*=1.96

A dietician read in a survey that 70.5% of adults in the U.S. do not eat breakfast at least 3 days a week. She believes that the proportion that skip breakfast 3 days a week is different than 0.705. To verify her claim, she selects a random sample of 71 adults and asks them how many days a week they skip breakfast.. 44 of them report that they skip breakfast at least 3 days a week. Test her claim at a = 0.10. The correct hypotheses would be: О Но:р 0.705 (claim) Но: р > 0.705 HA:p < 0.705 (claim) О Но: р — 0.705 HA:P + 0.705 (claim) Since the level of significance is 0.10 the critical value is 1.645 and -1.645 The test statistic is: (round to 3 places) The p-value is: (round to 3 places) The decision can be made to: O reject Ho O do not reject Ho The final conclusion is that: O There is enough evidence to reject the claim that the proportion that skip breakfast 3 days a week is different than 0.705. O There is not enough evidence to reject the claim that the proportion that skip…

An LED light bulb manufacturer claims that the average lifespan of its 60-watt LED light bulbs is 27,000 hours. A corporate watchdog group is suspicious of the company's claim and thinks that the true average lifespan of the 60- watt LED light bulbs produced by the company may be less than the advertised 27,000 hours. The group collected and tested a random sample of 211 light bulbs and found the average lifespan of the sample was 26,941 hours. Use the p-value method to test the hypothesis that the mean lifespan of this brand of 60-watt LED light bulb is less than 27,000 hours, using a = 0.1. Assume the standard deviation of the lifespan of all such light bulbs is known to be 370 hours. State the null and alternative hypothesis for this test. Ho: ? H₁: ? Determine if this test is left-tailed, right-tailed, or two- tailed. right-tailed two-tailed left-tailed Should the standard normal (z) distribution or Student's (t) distribution be used for this test? The Student's t distribution…

In random samples of 900 men and 400 women it is found that 99 men and 36 women suffer from kidney stones. Is there statistical evidence that the proportion of male kidney stone sufferers is greater than the proportion of female kidney stone sufferers? Use 5% significant level.

According to the American Lung association, lung cancer account for 28% of all cancer deaths in the US.  A new type of screening for lung cancer, computed tomography (CT), has been developed.  Medical researchers believe CT scans are scans are more sensitive than regular X-rays in pinpointing small tumors. The Cancer Center at the University of South Florida is currently conducting a clinical trial of 50,000 smokers nationwide to compare the effectiveness of CT scans with X-ray for detecting lung cancer (Today’s Tomorrows, Fall 2002).  Each participating smoker is randomly assigned to one of the two screening methods, CT or chest X-ray, and his or her progress is tracked over time.  The age at which the scanning method first detects a tumor is the variable of interest. A. Identify the data collection method used by the cancer researchers.        B. dentify experimental units of the study.  C. Identify the type of the variable measured.  D. Identify the population and sample.