1) In a poll to estimate presidential popularity, each person in a random sample of 1,000 voters was asked to agree with one of the following statements: 1. The President is doing a good job. 2. The President is doing a poor job. 3. I have no opinion. A total of 560 respondents selected the first statement, indicating
A study was conducted to determine if softly playing Mozart in the background enhanced retention while studying dates of historical significance. The data from the study is summarized below. No Mozart n = 20; x = 63.8; s = 4.4 Mozart n = 20; x = 64.2; s = 3.5 Assume the populations are normal with unequal vari
1) The following is sample information. Test the hypothesis that the treatment mean are equal. Use the .05 significance level. Treatment 1 Treatment 2 Treatment 3 8 3 3 11 2 4 10 1 5 3 4 2 T1= 29 T2= 11 T3= 16 TOTAL T=56 N1= 3 N=5 N=4 N=12 9.6 (MEAN) 2.2 (MEAN) 4 (MEAN) 15.8 FOR GRAND MEAN A. State the
The following data set represents the repairs costs in dollars for a random sample of 30 dishwasher. 41.82 52.81 57.8 68.16 73.48 78.88 88.13 88.79 90.07 90.35 91.68 91.72 93.01 95.21 95.34 96.5 100.05 101.32 103.59 104.19 105.62 111.32 117.14 118.42 118.77 119.01 120.7 140.52 141.84 147.06 a) Find the point of
An experiment involves selecting a random sample of 256 middle managers for study. One item of interest is annual income. The sample mean is computed to be $35,420 and the sample standard deviation is $2,050. Using this information, calculate the 95% confidence interval (rounded to the nearest $10). Interpret your findings.
The table gives the average low tempatures in January and July for twelve cities. Construct a 99% confidence interval for the mean temperature difference (January-July) between winter and summer. Assume the population are normally distributed. Cities JANUARY JULY Chhose the 99% confidence interval for the mean diffe
In regards to the stock market returns, what is the significance of the Law of Large Numbers? What do confidence intervals represent? What are the differences between z-statistics and t-statistics?
Piggybank would like to examine the required sample size needed to be able to estimate the mean dollars that each card holder will spend each month. it would like to be within plus or minus $10 of the true means with a 98% confidence level. the standard deviation is thought to be $500. how many card holders should be sampled?
1. Elwin Osbourne, CIO at GFS, Inc., is studying employee use of GFS e-mail for non-business communications. A random sample of 200 e-mail messages was selected. Thirty of the messages were not business related. The 95% confidence interval for the population proportion is _________. a.0.091 to 0.209 b. 0.108 to 0.192
a) A seed distributor guarantees 95% germination of the seeds he supplies. A retailer has an agreement with the distributor, under which he may test a random sample of 200 seeds for germination and send the whole batch back to the manufacturer if the proportion of germinating seeds is significantly below 95%. With a significance
(See attached file for full problem description with proper equations) An engineer was interested in comparing the variability of the power of a laser at current levels of 16 amps (X) and 20 amps (Y). To do so, random samples of 25 observations of power readings were obtained at each current level. The samples were taken hi
Ms. Maria Wilson is considering running for mayor of the town of Bear Gulch, Montana. Before completing the petitions, she decides to conduct a survey of voters in Bear Gulch. A sample of 400 voters reveals that 300 would support her in the November election. Estimate the value of the population proportion. Compute the sta
1. You are the manager of a tax preparation center. A vendor brings in a new software package that he says can reduce the amount of time spent preparing taxes. What would your null hypothesis be? With your null who is bearing the risk of Type I and Type II errors? 2. What is the value of establishing confidence intervals
6. The October 24, 1996 issue of The Wall Street Journal gave the following results for a poll: Clinton Dole Perot Undecided 52% 35% 6% 7% According to the article the above results were based on a nationwide survey of 1008 households. Determine a 95% confidence interval for each of the above results.
4. An automobile manufacturer gives a 5 year/60,000 mile warranty on its drive train. Historically, 7% of this manufacturer's cars have required service under this warranty. Recently, a design team proposed an improvement that should extend the drive train's life. A random sample of 200 cars underwent 60,000 miles of road tes
2. A company manufactures steel bolts that continuously feed an assembly line downstream. Historically, the thickness of these bolts follows a normal distribution with a standard deviation of 1.6 mm. A recent random sample of 10 observations yielded these values of thickness, in mm: 9.7 9.9 10.3 10.1 10.5 9.4 9.9 10.1
Refer to the sample results below for the measured nicotine contents of randomly selected filtered and non-filtered king-size cigarettes. All measurements are in milligrams. a. use a 0.05 significance level to test the claim that king-size cigarettes with filters have a lower mean amount of nicotine than the mean amount of nic
A discount store is trying to decide whether to use a single waiting line for available cashiers. The waiting times for 25 randomly selected customers was found to have a standard deviation of 1.7 minutes. Construct a 95% confidence interval for the population variance.
A College wished to know the number of library books borrowed by students over a term. 16 students were selected at random and the following data were obtained for the books they borrowed: 24, 22, 25, 25, 21, 26, 27, 22, 24, 23, 28, 23, 28, 25, 26, 21 (i) Calculate a 95% confidence interval for the population mean, . (ii)
The national average for the price of a gallon of unleaded regular gas is $1.16. I believe the price is higher in my area of the country. I want to test my claim by randomly selecting gas prices for 25 stations in my area. The following prices are: $1.27 $1.29 $1.16 $1.20 $1.37 1.20 1.23 1.19 1.20 1.24
What factors contribute to the calculation of confidence intervals? What is the relationship between confidence intervals and hypothesis testing?
8.54 Alice Chang and her colleagues (A. Chang, T. L. Rosenthal, R. H. Bryant, R. H. Rosenthal, R. M. Heidlage, and B. K. Fntzlcr. "Comparing High School and College Students' L.eisure In- wrests and Stress Ratings," Behavioral Research Therapy 31(2), 1993) tested 559 high school students using a leisure-interest checklist (LIC)
Consider the case where we have n observations, sampled from a binomial pdf (our parameter estimator can therefore be given by X/n). Assume that the margin of error is 6%. How many observations do we need for the margin of error for the proportion to be cut in half (to 3%)?
In a survey, 200 people were asked to identify their major source of news information; 110 stated that their major source was television news. a. Construct a 95% confidence interval for the proportion of people in the population who consider television their major source of news information. b. Determine how large a sample
In a recent survey of 1677 U.S. Internet users, 74% of the young tech elite (average age of 22) say their computer would be very hard to give up (PC Magazine, February 3, 2004). Only 48% say their television would be very hard to give up. a. Develop a 95% confidence interval for the proportion of the young tech elite that wou
Complaints about rising prescription drug prices caused the U.S. Congress to consider laws that would force pharmaceutical companies to offer prescription discounts to senior citizens without drug benefits. The House Government Reform Committee provided data on the prescription cost for some of the most widely used drugs (Newswe
Smith Travel Research provides information on the one-night cost of hotel rooms throughout the United States (USA today, July 8, 2002). Use $2 as the desired margin of error and $22.50 as the planning value of the population standard deviation to find the sample size recommended in (a), (b), and (c). a. Determine a 90% confid
Fifteen patients who suffer from high blood pressure were given a drug that is supposed to lower blood pressure. If X denotes the amount of a patient's decrease from his or her normal blood pressure and if the sample from 15 produced the estimate = 5 and s = 8, find a 95 percent confidence interval for using small sample meth
(See attached file for full problem description with proper symbols) --- Two sets of 100 students each were taught to read by two different methods. After instruction was over a reading test gave the following results: = 73.4, = 70.3, = 8, =10. Show that a 90 percent confidence interval for is
The weight of a product is measured in pounds. A sample of 50 units is taken from a batch. The sample yielded the following results: = 75 lbs., and s = 10 lbs. Calculate a 99 percent confidence interval for μ.