5. To test the null hypothesis that the average lifetime for a particular brand of bulb is 750 hours versus the alternative that the average lifetime is different from 750 hours, a sample of 75 bulbs is used. If the standard deviation is 50 hours and alpha is equal to 0.01, what values for x-bar will result in rejection of the
Sample size n = 3,200. 41% think that outsourcing is bad for U.S. businesses. 56% think outsourcing is good for U.S. businesses. 3% do not know. I think that the percent of those that think is good is lower. Assumption: Suppose that outsourcing can be deemed feasible if at least 73% of the population thinks that outsourci
8.17 Bowman Electronics sells electronic components for car stereos. They claim that the average life of a component exceeds 4,000 hours. To test this claim, they have selected a random sample of n = 12 of their components and have traced the life between installation and failure. The following data were obtained: 1,973
Summarize in words each of the following findings: 1. Group A = 52, Group B = 63, t = 4.33, p < .02. 2. Group A's mean SAT score was 558; Group B's was 457; Group C's was 688; F = 4.77, p < .001. 3. The Tukey test was significant at .01 for two groups (A and E).
8.8 Given the following null and alternative hypothesis Ho: μ = 1,346 HA: μ ≠ 1,346 α = 0.05 and _ X = 1,338 σ = 90 n =60 a. establish the appropriate decision rule based on z as a test statistic b. indicate the appropriate decision based on the sample information and
For each of the following situations, determine the margin of error: _ a. X = 2.47, and n = 12, confidence coefficient = 0.98, σ = 6.58 _ b. X = 13.9, and n = 21, confidence coefficient = 0.95, s = 2.33 _ c. X = 114.7, and n = 500, confidence coefficient = 0.80, s = 15.6 If you wis
Discuss the use of standard deviation. Explain how it might be useful to you in your research and how you would explain results using standard deviation. Also, how might it help you in interpreting someone else's research?
1. Find the standardized test statistic to test the claim that mean1 = mean 2. Two samples are randomly selected from each population. The sample statistics are given below. n1 = 50 n2 = 6 x1 = 31 x2 = 29 s1 = 1.5 s2 = 1.9 x has a line above it 2. In a recent survey in gun control laws, a random sample of 1000 women sho
The manager of a computer software company wishes to study the number of hours senior executives spend at their desktop computers by type of industry. The manager selected a sample of five executives from each of three industries. At the .05 significance level, can she conclude there is a difference in the mean number of hours s
An advertisement for a particular tax preparation software package claims you can complete your taxes in less than 56 minutes. A random selection of 49 individual's tax preparation times (using the software) was collected, and their mean was calculated to be 55 minutes. It is known that the standard deviation is 4 minutes. Test
Problem During a meeting, one hospital administrator indicated that 70% of the geriatric patients are males. a. What is the sample proportion of male patients? b. Assumiong that the administrator is correct, what is the probability that a sample of this size would have a sample proportion as extremem or more extre
Problem: Past records suggest that the mean annual income, mu1, of teachers in state of pennsylvania is less than or equal to the mean annual income, mu2, of teachers in Illinois. In a current study, a random sample of 15 teachers from pennsylvania and an independent random sample of 15 teachers from Illinois have been asked
EXAMPLE A recent national survey found that high school students watched an average (mean) of 6.8 videos per month. A random sample of 36 college students revealed that the mean number of videos watched last month was 6.2, with a standard deviation of 0.5. At the .05 significance level, can we conclude (test) that college stu
According to the historical data, the life expectancy in Belgium is less than or equal to the life expectancy in the United States. A new study has been made to see whether this has changed. Records of 260 individuals from Belgium who died recently are selected at random. The 260 individuals lived an average of 78.3 years with a
Use the five-step hypothesis testing procedure for the following exercise. Ms. Lisa Monnin is the budget director for Nexus Media, Inc. She would like to compare the daily travel expenses for the sales staff and the audit staff. She collected the following sample information. Sales ($) 131 135 146 165 136 142 Audit ($)
Refer to the null hypothesis as a theory that has been presented because the researcher believes it to be true or would like to use it as a basis for a future argument. It is critical to understand that a null hypothesis has not been proven on any level and thus the experiment. Additional special consideration is always given to
Problem A coin-operated drink machine was designed to discharge a mean of 7 ounces of coffee per cup. In a test of the machine, the discharge amounts in 12 randomly chosen cups of coffee from the machine were recorded. The sample mean and sample standard deviation were 6.85 ounces and 0.23 ounces, respectively. If we assume
Question One personality test available on the World Wide Web has a subsection designed to assess the "honesty" of the test-taker. After taking the test and seeing your score for this subsection, you're interested in the mean score, mu, among the general population on this subsection. The website reports that mu is 142, but
The General Social Survey is an annual survey given to about 1500 U.S. adults selected at random. Each year, the survey contains several questions meant to probe respondents' views of employment. A recent survey contained the question "How important to your life is having a fulfilling job?" Of the 240 college graduates surveyed,
A purchasing manager for a large university is investigating which brand of LCD projector to purchase to equip "smart" classrooms. Of major concern is the longevity of the light bulbs used in the projectors. The purchasing manager has narrowed down the choice of projector to two brands, Infocus and Proxima, and wishes to determi
Past records suggest that the mean annual income, mu 1, of teachers in state of Georgia is greater than or equal to the mean annual income, mu 2, of teachers in Indiana. In a current study, a random sample of 20 teachers from Georgia and an independent random sample of 20 teachers from Indiana have been asked to report their mea
Tourism is one consideration for Coffee Time's future. A survey of 1,233 visitors to Mumbai last year revealed that 110 visited a small café during their visit. Laura claims that 10% of tourists will include a visit to a café. Use a 0.05 significance level to test her claim. Would it be wise for her to use that claim in tryin
Each month the National Association of Purchasing Managers publishes the NAPM index. One of the questions asked on the survey to purchasing agents is: Do you think the economy is expanding? Last month, of the 300 responses 160 answered yes to the question. This month, 170 of the 290 responses indicated they felt the economy was
Two boats, the Prada (Italy) and the Oracle (U.S.A.), are competing for a spot in the upcoming America's Cup race. They race over a part of the course several times. Below are the sample times in minutes. At the .05 significance level, can we conclude that there is a difference in their mean times? Boat Times (minutes) Prada (
18. The management of White Industries is considering a new method of assembling its golf cart. The present method requires 42.3 minutes, on the average, to assemble a cart. The mean assembly time for a random sample of 24 carts, using the new method, was 40.6 minutes, and the standard deviation of the sample was 2.7. Using the
Two pediatricians want to investigate a new laboratory test that identifies streptococcal infections. Dr. J uses the standard culture test, which has a sensitivity of 90% and a specificity of 96%. Dr. M uses the new test, which is 96% sensitive and 96% specific. Review answer is Dr. J will correctly identify fewer people with
A screening test is used in the same way in two similar populations, but the proportion of false-positive results among those who test positive in population A is lower than that among those who test positive in population B. What is the likely explanation for this finding? Answer is The prevalence of disease is higher in popu
Problem 1 Use four decimal places in your answers for this problem. Eighteen (18) people in a department of 162 are fully trained in CPR and AED. A person shows signs of a heart attack. Five (5) people respond. What is the probability that NO (0) person who responded is trained to treat the victim? (Show all of your calcu
1. A random sample of 10 observations is selected from the first normal population and 8 from the second normal population. For a one-tailed test of hypothesis (.01 significance level) to determine if there is a difference in the population means, the degrees of freedom are A.18 B.17 C.16 D.None of the above 2. A random
Problem (Two tailed test) A decade-old study found that the proportion, p, of high school seniors who believed that "getting rich" was an important personal goal was 80%. A researcher decides to test whether or not that percentage still stands. He finds that, among the 225 high school seniors in his random sample, 164 believe