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What amount of time represents the highest 30% of excavator working time? The rental fee of each excavator is 200 dollars per hour, if the city rents 3 excavators, what is the expected rental fee per
A sample of 35 different payroll departments found that employees worked an average of 240.6 days a year. If the population standard deviation is 18.8 days, find the 90% confidence interval for the
A study of 65 bolts of carpet showed that their average length was 78.2 yards. The standard deviation of the population is 1.6 yards. Which of the following is the 80% confidence interval for the me
Jennifer wants to find a 95% confidence interval for the time it takes her to get to work. She kept records for 30 days and found her average time to commute to work was 20.5 minutes with a standard
A student looked up the number of years served by 35 of the more than 100 Supreme Court justices. The average number of years served by those 35 justices was 13.8. If the standard deviation of the e
The average age of these millionaires was 54.8 years. If the standard deviation of the entire population of millionaires is 7.9 years, find the 95% confidence interval for the mean age of all United
What is the probability that Fischer wins the match? What is the PMF of the duration of the match?
The average number of years served by those 35 justices was 13.8. If the standard deviation of the entire population is 7.3 years, find the 95% confidence interval for the average number of years se
A job shop consists of three machines and two repairmen. The amount of time a machine works before breaking down is exponentially distributed with mean 10. If the amount of time it takes a single r
Let X and Y be independent random variables with means u1=1 and u2=2, standard deviations equal to 2 and 1. Find the distributions of the variables
Let X be a normal random variable with a mean of 210 and a standard deviation of 36. What value of X is less than 71% of the values? a. 180.8 b. 190.2 c. 202.4 d. 229.8
A process is to be monitored with standard values m (mu) = 10 and s = 2.5. The sample size is n = 2. Find the center line and control limits for the X-bar chart.
An automobile dealer sells used cars with an average value of $12400. The prices are normally distributed with a standard deviation of $3280. What percentage of the cars will sell for $15000 or more
During a recent health fair a group of participants responded to two questions: 1) Asthma attack (Yes/No) and 2) Social economic status (High, Middle, Low). The survey results are shown in the follo
Let X be the number of customers of a car salesman over a one-day period. Suppose that X has a Poisson distribtution with parameter \lambda = 3. Furthermore, suppose that one customer in five, on av
Consider two independent variables X and Y, where X is uniformly distributed on the interval [-1,1] and Y is exponentially distributed with mean 3. Find the joint density function for the pair (X, Y
The manufacturing of semiconductor chips produces 2% defective chips. Assume the chips are independent and that a lot contains 1000 chips.
It is estimated that 56% of the children between the ages of 3 and 5 years are already enrolled in school. In a sample of 350 children what is the probability that at least half are enrolled in scho
The time for a professor to grade an exam is normally distributed with a mean of 12.6 minutes and a standard deviation of 2.2 minutes. The interval around the mean that contains 95% of the times nee
The time for a professor to grade an exam is normally distributed with a mean of 12.6 minutes and a standard deviation of 2.2 minutes. The interval around the mean that contains 95% of the times ne
A production process produces items, of which 6% are defective. A random sample of 160 items is selected every day and the number of defective items, say X, is counted. Using the normal approximatio
Catherine Chao, Director of Marketing Research, is evaluating consumer acceptance of a new toothpaste package. She plans to use a 80% confidence interval estimate of the proportion of households whi
In relation to the quality of data entry options, i.e. databases (such as EpiInfo, ACCESS) and spreadsheets (such as Excel), which of the following statements is true?
Having never smoked more than five cigarettes previously and having smoked five or less cigarettes previously are __________ events.