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The statistics showed that students studied an average of 19 hours per week with a standard deviation of 14 hours. What is the probability that a sample mean would exceed 19 hours per week?
A reporter wants to know whether the difference between the two percentages is statistically significant. Does the question make sense? Can you answer it with the info given?
What is the probability that a randomly selected 18-ounce bag of chocolate chip cookies contains fewer than 1400 chocolate chips?
What do you conclude about the claim below? Do not use formal procedures or exact calculations. Use only the rare event rule and make a subjective estimate to determine whether then event is likely.
What is ?, the electromotive efficiency to three significant figures? Open the hint panel below for the definition of electromotive efficiency.
What is the percentage of the total area under the normal curve within plus and minus 1.6 standard deviations of the mean?
Using two independent samples, we test for a hypothesized difference between two population means. The population standard deviations are unknown but assumed equal.
An investigation of the effectiveness of a training program to improve customer relationships included a pre-training and post-training customer survey. Seven customers were randomly selected and co
A hospital spokesperson claims that the standard deviation of the waiting times experienced by patients in its minor emergency department is no more than 0.5 minute. A random sample of 22 waiting ti
For a one-tailed hypothesis test, the critical z-value of the test statistic is -1.48. Which of the following is true about the hypothesis test?
What is the decision rule at the 0.01 level of significance to test if the new design increased the absorption amount of the sponge?
Using a 5% level of significance and a sample size of 26, what is the critical value for a one-tailed hypothesis test?
The table below lists the numbers of audience impressions listening to songs and the corresponding numbers of albums sold. Does it appear that album sales are affected very strongly by the number of
A student wanted to construct a 95% confidence interval for the average age of students in her statistics class. She randomly selected 11 students. Their average age was 21.4 years with a standard d
Recently, a university surveyed recent graduates of the English Department for their starting salaries. Four hundred graduates returned the survey. The average salary was $25,752. The population sta
A bank wishes to estimate the mean credit card balance owed by its customers. The population standard deviation is estimated to be $313. If a 98 percent confidence interval is used and an interval o
A group of statistics students decided to conduct a survey at their university to find the average (mean) amount of time students spend studying per week.
An accounting firm is planning for the next tax preparation season. From last year's returns, the firm collects a systematic random sample of 100 filings. The 100 filings showed an average preparati
The distribution of the annual incomes of a group of middle management employees approximated a normal distribution with a mean of $39,570 and a standard deviation of $798. About 65 percent of the i
How many main effects and interactions could you have in a 4 x 6 factorial design?
What internal and external validity threats did the researchers address in their design? How did they address them? Are there threats they did not address? If so how does the failure to address the
A sample of 20 items provides a sample standard deviation of 5. Compute the 95% confidence interval estimate of the population variance.
Construct a 95% interval estimate of the ratio of the population variances.