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Quiz #1D Semester 061 Dept of Mathematical Sciences Stat319: Intro to Prob & Stat for Engineers & Scientists Instructor: Musawar Amin Malik Section: 2 (8-8.50am), 4 (9-9.50am) Name:_______________________ ID#:______________ 1 Directions: This quiz is designed for 45 minutes. Please answer all questions True/false and multiple choice (circle the best answer) 1. A distribution is said to be symmetric when the sample mean and the population mean are equal. (True/False) 2. If after graphing the data for a quantitative variable of interest, you notice that the distribution is highly skewed in the positive direction, the measure of central location that would likely provide the best assessment of the center would be the median. (True/False) 3. Which of the following is an acceptable format for setting up class boundaries for a frequency distribution? a. 20 and under 40 b. 20 – 40 c. 200 – 299.99 d. All of the above. 4. A study was recently conducted in which makers of toothpaste tracked sales for the month at different stores in a market area. The variable of interest was the number of units sold. The numbers ranged from 1,200 to 22,700. In this case, the stems in a stem & leaf diagram might be values such as 1 and 22 while the leaves would be 200 and 700. (True/False) 5. One of the differences between a stem & leaf diagram and a histogram is that even for variables involving a large number of different values, the stem & leaf diagram shows the individual data values whereas the histogram requires you to group the data and lose the individual values. (True/False) 6. A histogram can be constructed for data that are either quantitative or qualitative. (True/False) Solving Questions (show your calculations and final answer) 7. The following sample data reflect electricity bills for ten households in San Diego in March. Determine three measures of central tendency for these sample data. Then, based on these measures, determine whether the sample data are symmetric or skewed. Quiz #1D Semester 061 Dept of Mathematical Sciences Stat319: Intro to Prob & Stat for Engineers & Scientists Instructor: Musawar Amin Malik Section: 2 (8-8.50am), 4 (9-9.50am) Name:_______________________ ID#:______________ 2 Directions: This quiz is designed for 45 minutes. Please answer all questions 8. The AMI Company has two assembly lines in its Kansas City plant. Line A produces an average of 335 units per day with a standard deviation equal to 11 units. Line B produces an average of 145 units per day with a standard deviation equal to 8 units. Based on this information, which line is relatively more consistent? 9. The number of days that houses stay on the market before they sell in Houston is bell-shaped with a mean equal to 56 days. Further, 95 percent of all homes are on the market between 40 and 72 days. Based on this information, find the standard deviation for the number of days that houses stay on the market in Houston. 10. The following data reflect the number of customers who return merchandise for a refund on Monday. Note these data reflect the population of all 10 Mondays for which data are available. Based on these data, calculate the standard deviation. 11. The credit card balances for customers at State Bank and Trust has a mean equal to $800 and a standard deviation equal to $60.00. Kevin Smith’s balance is $1,352. Based on this, find his standardized value (z-score). Quiz #1D Semester 061 Dept of Mathematical Sciences Stat319: Intro to Prob & Stat for Engineers & Scientists Instructor: Musawar Amin Malik Section: 2 (8-8.50am), 4 (9-9.50am) Name:_______________________ ID#:______________ Directions: This quiz is designed for 45 minutes. Please answer all questions 3