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Standard deviation of the percentage who say "Yes" from 7% to 3.5%? Explain to someone who knows no statistics the advantage of taking a larger sample in a survey of opinion.
In a large section of a statistics class, the points for the final exam are normally distributed. Find the lowest score on the final exam that would qualify a student for an A, a B and a C
The Ace Wrecking Company operates a large fleet of trucks. These trucks average one call for mechanical service every 4 hours. Trucks generate revenue for Ace at the rate of $20 per hour. Ace's ace
Considering the following data using weighted moving average (4 quarters; 0.4, 0.3, 0.2, and 0.1; where 0.5 is the weight for the most recent quarter)Calculate Mean Absolute Deviation (MAD)
18% have three or more sets. If two households are chosen at random, what is the probability that at least one has a television set?
At a certain university, the average costs of books was $340 per student last semester and the population standard deviation was $90. This semester a sample of 45 students revealed and average cost
In this problem we want to run a test of goodness of fit to check whether the coats in the consignment follow the indicated probabilities.
A statistics practitioner conducted a two-factor analysis of variance experiment with a =4, b = 3, and r = 8. Test at the 5% significance level to determine whether factors a and b interact.
The mean operating cost for the fleet of delivery trucks because the sample mean is contained in the interval. Do you agree? How would you interpret this confidence interval?
Test the claim of the engineering firm. Perform an appropriate hypothesis test, showing the necessary calculations and/or explaining the process used to obtain the results.
the average length of a long distance telephone call is 28 minutes with a standard deviation of five minuts. assuming the call times are normally distributed, what percentage of calls are longer tha
The average monthly gasoline purchase for a family with two cars is 90 gallons. The statistic has a normal distribution with a standard deviation of 10 gallons. Find the probability that the family
Active ingredient in 1 pound of each chemical are given in a different file (information included below). It is necessary that at least 100 pounds of chemical to be used. How do I se this up using e
a computer store has 50 printers of which 75 are laser printers and 15 are ink jet printers. if a group of 10 printers is chosen at random from the store, find the mean and variance of the number of
A survey was mailed to a total of 400 students; 100 were randomly selected from each of the freshman, sophomore, junior and senior classes last semester. What sampling method was used?
If we have a random sample of 6 patients who press call buttons. What is the probability that under 4 of them will have to wait five minutes to more for staff to respond?
In testing a new drug, researchers found that 10% of all patients using it will have a mild side effect. A random sample of 12 patients using the drug is selected. Find the probability that: (A) ex
the heights of 1000students are normally distributed with a mean of 174.5 centimeters and a standard deviation of6.9 centimeters.assuming that the heights are recorded to the nearest half-cm,how man
If the store orders four copies of the magazine, is it better to order four than three copies of the magazine. Explain.
A company selects five of the machines at random, thinking all are in working condition. What is the probability that all five of the machines are nondefective?
Thirty randomly selected students took the calculus final. If the sample mean was 79 and the standard deviation was 8.5, construct a 99% confidence interval for the mean score of all students.
The correlation between the two variables is 0.4. Hourly earnings are regressed on years of education. What is the slope of the OLS regression line?
Of 150 adults who tried a new video game for the summer market, 87 rated it excellent. Of 200 teens sampled, 123 rated it excellent. Using the .10 level of significance, can we conclude there is a s
One of the herpetologists fears that pollution might be affecting the natural growth of the pythons. Do you think this sample result is unusually small? Explain. Show work.
The manager of a department store wants to determine what proportion of people who enter the store use the store's credit card for their purchases. What size sample should he take so that at 99% con