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Which structure is found in all prokaryotic cells?

What is the best definition of dysbiosis?

The yield of a chemical process is being studied. From previous experience, yield is known to be normally distributed and σ = 3. The past 5 days of plant operation have resulted in the following percent yields: 91.6, 88.75, 90.8, 89.95, and 91.3. Find a 95% two-sided confidence interval on the true mean yield.

In the 16/17 season, Valencia CF (Spanish soccer club) had 19 home games. The number of fans who visited 10 football matches at the Mestalla stadium (home stadium of Valencia CF) is shown in the table below. 43602 34456 42070 20512 30823 27446 43333 20570 25694 32221                   Calculate 90% lower confidence limit for variance. 

A manufacturer is interested in the output voltage of a power supply used in a PC. Output voltage is assumed to be normally distributed with standard deviation 0.3 volt, and the manufacturer wishes to test volts against volts, using n=16 units. The acceptance region is . Find the value of .

Medical researchers have developed a new artificial heart constructed primarily of titanium and plastic. The heart will last and operate almost indefinitely once it is implanted in the patient’s body, but the battery pack needs to be recharged about every 4 hours. A random sample of 50 battery packs is selected and subjected to a life test. The average life of these batteries is 4.05 hours. Assume that battery life is normally distributed with standard deviation σ = 0.2 hour. Is there evidence to support the claim that mean battery life exceeds 4 hours? Use α = 0.05. What is the P-value for the test?

Two different water supplies 1 and 2 are being investigated for concentrations of dangerous chemicals.  The existing claim is that both supplies contain the same amount.  We want to conduct a hypothesis test to see if supply 2 has larger amounts of these chemicals at 5% significance level.  Assume both populations are independent and normal.  To this end, we collect a simple random sample from each process.

A group of 15 students has performed an experiment, they measured the coefficient of thermal expansion for aluminum. The results are as follows:  22.0 25.9 25.6 23.1 22.7 25.6 24.9 21.9 26.1 24.3 23.5 20.7 21.4 23.5 20.4   Is there strong evidence to conclude that the standard deviation in this experiment exceeds 3 at significance level of 0.05? Find the P-value for this test. 

An article in the ASCE Journal of Energy Engineering [“Overview of Reservoir Release Improvements at 20 TVA Dams” (Vol. 125, April 1999, pp. 1–17)] presents data on dissolved oxygen concentrations in streams below 20 dams in the Tennessee Valley Authority system. The observations are (in milligrams per liter): 5.0, 3.4, 3.9, 1.3, 0.2, 0.9, 2.7, 3.7, 3.8, 4.1, 1.0, 1.0, 0.8, 0.4, 3.8, 4.5, 5.3, 6.1, 6.9, and 6.5. Test the hypothesis versus . Use . Is it possible to reject hypothesis at the 0.01 level of significance? Find the P-value.

In a random sample of 500 handwritten zip code digits, 464 were read correctly by an optical character recognition (OCR) system operated by the U.S. Postal Service (USPS). USPS would like to know whether the rate is at least 90% correct. Do the data provide evidence that the rate is at least 90% at significance level of 0.05? Find the p-value of the test.