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A pharmaceutical company is testing the effectiveness of a new drug for lowering cholesterol. As part of this trial, they wish to determine whether there is a difference between the effectiveness fo
Research has shown that the people often see a correlation between two events when one does not really exist. Why do you think this happens?
The quality-control manager at a light bulb factory needs to determine whether the mean life of a large shipment of light bulbs is equal to 375 hours. The population standard deviation is 100 hours.
What is the probability that the shoplifter is a first time offender, given that the shoplifter is a male?
Describe a hypothesis you have related to the area of psychology in which you are predicting a correlation. What is the specific nature (direction) of the correlation.
recent study of 750 Internet users in Europe found that 35% of Internet users were women. What is the 95% confidence interval estimate for the true proportion of women in Europe who use the Internet
Use the steps of hypothesis testing, (b) figure the effect size for the study; and (c) explain your answers to parts (a) and (b) to someone who has never had a course in statistics.
On average a can of paint contains 10% of a checmical. How many cans of paint should the sample contain if the researcher wants to be 98% certain of being within 1% of the true proportion of this ch
The playing time X of classical CDs has the normal distribution with a mean of 54 and a standard deviation of 5; the N(54, 5) distribution. What is the relative frequency of classical CDs with a pla
Suppose that the firm wishes to choose a small sample of driving distances from the past year and carry out a hypothesis test for its suspicion. State the null hypothesis and the alternative hypothe
Normal distribution with a mean of 400 and a standard deviation of 100. The top 3% of students receieve $500. What is the minimum score you would need to receive this money?
A random sample of 5000 people found that 2000 were unhappy with drive through service at a popular restaurant. What is the value of the sample proportions, p-hat?
Chicken Delight claims that 90 percent of its orders are delivered within 10 minutes of the time the order is placed. A sample of 100 orders revealed that 82 were delivered within the promised timef
A company purchases shiments of machine components and uses this acceptance sampling plan: randomly select and test 23 components and accept the whole batch if there are fewer than 3 defectives. if
If the gender-selection method has no effect and boys and girls are equally likely, find the mean number of boys born in groups of 152. Round to the nearest whole number.
In the past an autoobile repair shop owner has noticed that sales increased ats certain economic indicators decreased. Based on forecasts of these economics indicators and past observations, the own
A sample of 300 cars traveling southbound on the New Jersey Turnpike yesterday revealed that 170 were driven by men. At the 0.01 significance level, can we conclude that a larger proportion of men w
Use a signifcance level of 95% (one-tailed). Does the use of a single line appear to reduce the variation among waiting times?
The batteries used in a digital watch have an operating life that is normally distributed. Find a 90% confidence interval for the population mean.
The quality-assurance department found in a sample of 50 customers at the Warren Road MacBurger that the mean waiting time was 2.75 minutes. At the 0.05 significance level, can we conclude that the
What is the 95% confidence interval estimate of the mean time it takes an individual to complete a federal income tax return?
At the time she was hired as a server at the Grumney Family restaurant, Beth Brigden was told, "You can average at least $20 a day in tips." Over the first 35 days she was employed at the restaurant
what is the balance in his account after the withdrawal of June 30 ,1999, if the interest rate is 9% until March 31, 1995 and 6% quarterly afterwards?
The weights of eggs produced on a farm are normally distributed with a mean of 1.4 ounces and a standard deviation of 0.4 ounces. How many 1200 eggs are within 2 standard deviations of the mean?
Metropolitan areas and used a bar chart to illustrate the differences. What type of statistics was shown? What activities did the newspaper use to make the report?