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A random sample of n = 57 observations produced a mean x = 30.8 and a standard deviation s=2.3 Find a 90% confidence interval for population mean µ.
The lengths of pregnancies are normally distributed with a mean of 268 days and standard deviation of 15 days, if 64 women are selected, find the probability that they have a mean pregnancy between
Two students were asked to rate six different television shows on a scale from 1 to 10 points, with higher values ranking ahead of lower values. Compute the sum of squares of the difference in ranks
Every time you go to a beach for vacation, you take home a little sand to keep as a souvenir. Over your lifetime, you have done this exactly 100 times. On each visit the weight of sand you take home
An economist wants to estimate the mean income for teh first year work for a college graduate who has had the profound wisdom to take a statistics course.
Let A, B, and C be independent random variables, uniformly distributed over [0,4], [0,3], and [0,6] respectively. What is the probability that both roots of the equation Ax2+Bx+C=0 are real?
Find the sum of the positive and negative rank sums as in a Wilcoxon signed-rank test.
Suppose that in one small town the average income is $34,200 with a stansard deviation of $2200. What percent of housholds between $29,800 and $38,600?
The average number of pounds of meat a person consumes a year is 218.8 with a standard deviation of 25 pounds. Assume normal distribution. if a sample of 40 people is selected, what is the probablil
A researcher believes exercise reduces anxiety in women. She identifies a group of women who had not exercised before but are now planning to begin exercising. she gives them a 50- item anxiety inve
Chicken Delight claims that 77 percent of its orders are delivered within 10 minutes of the time the order is placed. A sample of 60 orders revealed that 43 were delivered within the promised time
The mean time between failures (MTBF) is the expected time between a repair and the next failure of a component. MTBF at this time in testing =_______hours
The average wage of a construction worker is $11.76 with a standard deviation of $2.72. Assume normally distributed. What is the probability that a randomly selected worker makes more than $12.55
What is the null hypothesis? Assume a directional hypothesis is warranted. What is the null hypothesis assuming a non-directional hypothesis?
Estimate the probability that a randomly selected prime-time television show will be interrupted with a news bulletin.
Assume that women's heights are normally distributed with a mean of 63.5in, and a standard deviation of 2.4in. If a woman is randomly selected, find the probability that her height is less than 64 in
Find the percentage of women meeting the height requirement. Are many women being denied the opportunity to join this branch of the military because they are too short or too tall?
Suppose that 97% of Monarch butterflies migrate to Mexico in winter. What is the smallest sample size required to ensure that the sample proportion is normally distributed?
A medical researcher wants to know whether a new exercise regimen has an effect on the pulse rate of women between 75 and 80 years old.
The lottery commissioner's office in a state wanted to find if the percentages of men and women who play the lottery are often different. A sample of 500 men taken by the commisioner's office showed
On each visit the weight of sand you take home (measured in ounces), varies, but follows a U(10-sqt(48)/2, 10+sqt(48)/2) distribution. Assuming the amounts you take home on each trip are independent
A manufacturer of disk drives for notebook computers wants a MTBF of at least 50,000 hours. Recent test results for 15 units were one failure at 10,000 hours, one at 24,000 hours, and two more at 45
Identify the random variable along with the measurement scale. Can we conclude the median cholesterol levels of the population are greater than 200?
Assume that the number of networks errors experienced in a day on a local area network (LAN) is distributed as a Poisson random variable. The mean number of network errors experienced in a day is 2.