(Answer all questions: Q1-Q3 covers ch.1, Q4-Q6 covers ch.3, Q7-Q9 covers Ch.6, Q10-Q12 covers ch.7) 1 2 3 4 5 Can the terms descriptive statistics and inferential statistics be used interchangeably? (explain your answer) For each of the following situations, would you collect information using a sample or a population, why? a EC 112 is a course taught at a university, Professor X has taught nearly 1500 students in the course over the past 5 years. You would like to know the average grade for the course b As part of your research project, you need to report the average profit as a percentage of revenue for the #1 ranked corporation in the Fortune 500 for each of the last 10 years c You are looking forward to graduation and your first job as a salesperson for one of 5 large pharmaceutical corporations. Planning for your interviews you will need to know about each company's mission, profitability, products and markets d You are shopping for a new MP3 player such as the Apple iPOD. The manufacturer advertise the number of music tracks that can be stored in the memory. Usually, the advertisers assume relatively short, popular songs to estimate the number of tracks that can be stored. You, however, like Broadway musical tunes and they are much longer. You would like to estimate how many Broadway tunes will fill in your MP3 player A company was studying the demographics of their customers. As part of the study, they collected the following variables: gender, marital status, credit rating (low, medium, high), annual income, and age. Label each variable as qualitative or quantitative, discrete or continuous, and nominal, ordinal, interval, or ratio. The enrolments of the 13 public universities in the state of Ohio are listed below. University of Akron 26,666 Bowling Green State University 17,298 Central State University 2,152 University of Cincinnati 33,347 Cleveland State University 17,529 Kent State University 27,706 Miami University 16,924 Ohio State University 56,387 Ohio University 25,223 Shawnee State University 4,630 University of Toledo 21,500 Wright State University 16,762 Youngstown State University 13,813 a Is this a sample or a population? b What is the mean enrolment? c What is the median enrolment? d What is the range of the enrolments? e Compute the standard deviation. A company's human resources department was interested in the average number of years that a person works before retiring. The sample of size 11 follows: Based on the values of the arithmetic mean, median, and mode, what is the most likely shape of the distribution 6 The following frequency distribution reports the electricity costs for a sample of 50 two bedroom apartments in during May last year Cost 80 up to 100 100 up to 120 120 up to 140 140 up to 160 160 up to 180 180 up to 200 a b c Frequency 3 8 12 16 7 4 Estimate the mean cost Estimate the standard deviation Use the Empirical Rule to estimate the proportion of costs within two standard deviations of the mean? 7 The sales of Lexus cars in the area follow a Poisson distribution with a mean of 3 per day. a What is the probability that no Lexus is sold on a particular day? b What is the probability that for 5 consecutive days at least one Lexus is sold? 8 Suppose the National Hurricane Centre forecasts that hurricanes will hit the strike area with a 0.95 probability a What probability distribution does this follow? b If there are 10 hurricanes this season, what is the probability that all reach the strike area? c What is the probability at least one of 10 hurricanes reaches land outside the strike area? 9 Explain what is meant by this statement: \"There is not just one normal probability distribution but a \"family\" of them\" 10 A recent report indicated a typical family of four spends 490 per month on food. Assume the distribution of food expenditures for a family of four fold a normal distribution, with a standard deviation of 90 per month a What percent of families spend less than 430 per month on food? b What percent spend between 430 and 600 per month on food? c What percent spend between 500 and 600 per month on food? 11 An alarm in a household activates once every 200 days on average. Assume this activation follows an exponential distribution. What is the probability that a There will be an alarm within the next 60 days? b At least 400 days will pass before the next alarm? c It will be between 150 and 250 days until the next warning