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The time it takes for a statistics professor to mark a single midterm test is normally distributed with a mean of 4.8 minutes and a standard deviation of 2.5 minutes. There are 59 students in the pr
You are going to play a game where you bet a dollar and get to flip a coin ten times. If you get four heads in a row, you win. If you make the tenth flip without getting four heads in a row, you los
If X1 and X2 are independent random variables, X1 has a chi-square distribution with 3 degrees of freedom, and X1 + X2 has a chi-square distribution with 7 degrees of freedom. Prove that X2 has a ch
A health researcher wanted to know if there was a difference in success rates between three methods of quitting smoking: A, B, and C. She designed a study with 15 participants, 5 in each group, and
How should she explain this result to her supervisors if they are unfamiliar with hypothesis testing involving a sample of more than one individual or confidence intervals?
Use the five steps of hypothesis testing and show all work. Explain the logic of what you have done to a person who is unfamiliar with inferential statistics.
In a series of 40 payments the first 10 payments are 10 each, the second 10 payments are 20 each, the third ten payments are 30 each, and the final 10 payments are 40 each. The payments are equally
For the first 9 months of 2009 the account earned i^(12)=.105, and since then the account has been earning i^(12)=.12. Find the balance in the account on each of the following days:
If we have independent random samples n1=6 and n2=2 which are normally distributed and the sample variances are s21 = 5 and s22 = 15, can we assume σ21=σ22?
If the total is 17, then I roll two more dice and add that to the total. If these two bonus dice total 20, then the score of that game is 37. Of ten thousand games, what is the average score? Both a
Assume that all U.S. children are included in this survey and that this information is true for the current population. If one child is selected at random, what are the two complementary events and
According to a survey, 30 % of adults are against using animals for research. Assume that this result holds true for the current population of all adults. Let x be the number of adults who are again
An insurance company has 5000 policyholders who have had policies for at least 10 years. Over this period there have been a total of 12200 claims on these policies. Assuming a Poisson Distribution f
A researcher is interested in whether listening to music helps or hinders test-performance. To control for differences in cognitive level, this researcher decides to use a within-participants design
The purpose of the quality control sampling of the Widget production lines is to determine whether the lines are malfunctioning or not. Namely, if the mean length of the sample is too different from
Shear-strength measurements for spot welds of a certain type have been found to have an approximate normal distribution with standard deviation 10 psi. If 10 test welds are to be measured, find the
Assuming these estimates are correct, find the probability that their reception will suffer bad weather or a disruptive incident.
An extensive study of the cost of health care in the United States presented data showing that the mean spending per Medicare enrollee in 2003 was $6,883 (Money, Fall 2003).
Each of the following provides a statistical hypothesis, the observed test statistic and corresponding degrees of freedom, and the true population parameter(s), which was unknown to the experimenter
If the consulting firm tells you the sample mean for the Medicare enrollees it interviewed was $7500, would you question whether the firm followed correct simple random sampling procedures?
An airplane holds 20 passengers. The probability a passenger will not show up is .1 If the airline sells 25 tickets for the flight, what is the expected number of passengers that show up?
How large a sample should be taken to estimate the proportion of smokers in the population with a margin of error of .02 (to the nearest whole number)? Use 95% confidence.
A popular band on tour played a series of concerts in large venues. They always drew a large crow, averaging 21,359 fans. While the band did not announce the standard deviation, which of these value
Based on the confidence interval from part (a), does it appear that the population mean amount spent per day by families visiting Niagara Falls differs from the mean reported by the American Automob