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Scores on a university exam are Normally distributed with a mean of 68 and a standard deviation of 9. Using the 68-95-99.7 rule, what percentage of students score above 77?
From the probability distribution, find the mean and standard deviation for the random variable x, which represents the number of cars per household in a town of 1000 households.
The nine brand B cars that were tested averaged 32.1 mpg, and the standard deviation was 4.3 mpg. At =0.01, should it conclude that brand A cars have lower average gas mileage than do brand B cars?
Assume the heights of women normally distributed with a mean of 63.6 inches and a standard deviation of 2.5 inches. The U.S. Army requires that the heights of women between 58 and 80 inches. If a wo
Assume that the salaries of elementary school teachers in the United States are normally distributed with a mean of $31,000 and a standard deviation of $3000. If 100 teachers are randomly selected,
In a recent study of 71 eighth graders, the mean number of hours per week that they watched television was 18.7 with a standard deviation of 5.8 hours. Find the 99% confidence interval.
Construct a 98% confidence interval for the population mean, M. Assume the population has a normal distribution. A random sample of 20 college students has mean annual earnings of $3480 with a stand
A survey of 600 non-fatal accidents showed that 166 involved the use of a cell phone. Construct a 99% confidence interval for the proportion of fatal accidents that involved the use of a cell phone.
We determined the sodium content of 15 boxes of corn flakes 300 grams. The data (in milligrams) are: 128.77, 131.15, 129.65, 132.33, 130.54, 130.72, 131.67, 133.02, 127.98, 130.12, 129.37, 129.91, 1
The Ohio Department of Agriculture tested 203 fuel samples across the state in 1999 for accuracy of the reported octane level. For premium grade, 14 out of 105 samples failed (they didn't meet ASTM
The true weight of "10-pound" sacks of potatoes processed at a certain packaging house follows a normal distribution with mean of 10.1 pounds and standard deviation of 0.2 pounds.
Exposure of certain fruit fly population to an insecticide has produced 2 kinds of mutations: 20% have wing mutations, 15% have an eye mutation and 5% have both. A fly is selected at random. If the
If 20% of all seams need reqorking, what is the probability that rivets is defective? How small should the probability of a defective be to ensure that only 10% of all seams need reworking?
When do we use Chevbychev's theorem? with what kinds of problems? and for what purpose? please explain clearly for lifesaver.
Please explain both Poisson and exponential distributions and the difference between them. Please include extensive details for lifesaver.
A post office has two counters where customers can buy stamps, etc. If you are interested in the number of customers in the two queues that will form for the counters, what would you take as sample
A screening test shows a positive result in 95% of all cases when disease is present and in 20% of all cases when it is not. When adminestered to a large number of people, 21.5% of the results were
Suppose that in front of a hotel in a large city, successive 20 second intervals constitute independent trials, in which either a single cab will arrive (with probability 0.2), or no cabs will arriv
By how much could the value 420 be decreased without affecting the value of the sample median? (Enter infinite if there is no limit to the amount.)
A system is composed of 5 components, each of which is either working or failed. Consider an experiment that consists of observing the status of each component, and let the outcome be given by a vec
In how many ways can Waldo eat seven evening meals at these restaurants, assuming that he wishes to try different restaurant each night and also that he wishes to alternate between Italian and Chine
What are the combinations which lead to the sum 12? Is the observation of the Chevalier de M ´er ´e just an exception due to randomness or is his argumentation wrong? Define a suitable sa
Using a two-tailed test with α = .05, is there a significant difference between the two treatment conditions?