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Stat 101 – Sheet 4 King Saud University Almajmaa’h Engineering College STAT 101 1430/2009 --------------------------------------------------------------------------------------------------------------------------------------- Sheet (4) 1. The following data set belongs to a population: 5 -7 2 0 -9 16 10 7 Calculate the range, variance and standard deviation. 2. The following data set belongs to a sample: 14 18 -10 8 8 -16 Calculate the range, variance and standard deviation. 3. The following data give the prices of seven textbooks randomly selected from a University bookstore $89 $57 $104 $73 $26 $121 $81 a) Find the mean for these data. Calculate the deviations of the data values from the mean. Is the sum of these deviations zero? b) Calculate the range, variance and standard deviation. 4. The following data give the numbers of car thefts that occurred in a city in the past 12 days. 6 3 7 11 4 3 8 7 2 6 9 15 Calculate the range, variance and standard deviation. 5. The following data give the temperature (in Fahrenheit) observed during eight wintry days in a Midwestern city. 23 14 6 -7 -2 11 16 19 Compute the range, variance and standard deviation. Dr. SaMeH Page 1 Stat 101 – Sheet 4 6. Using the population formulas, find the mean, variance and standard deviation for the following grouped data. x 2-4 5-7 8-10 11-13 14-16 f 5 9 14 7 5 7. Using the sample formulas, find the mean, variance and standard deviation for the grouped data displayed in the following table. x 0 to less than 4 4 to less than 8 8 to less than 12 12 to less than 16 16 to less than 20 20 to less than 24 f 17 23 15 11 8 6 8. The following table gives information on the amounts (in dollars) of electrical bills for August 2002 for a sample of 50 families. Amount of electrical Bill (dollars) 0 to less than 20 20 to less than 40 40 to less than 60 60 to less than 80 80 to less than 100 Number of families 5 16 11 10 8 Find the mean, variance and standard deviation. 9. For 50 airplanes that arrived late at an airport during a week, the time by which they were late was observed. In the following table, x denotes the time (in minutes) by which an airplane was late and f denotes the number of airplanes. x 0 to less than 20 20 to less than 40 40 to less than 60 60 to less than 80 80 to less than 100 f 14 18 9 5 4 Find the mean, variance and standard deviation. Dr. SaMeH Page 2