Grouped Data Problems

Find the mean and standard deviation of the following quantitative frequency distributions. These problems were adapted from those on pages 146 to 148 of Michael Sullivan, Fundamentals of Statistics, 2nd edition, Pearson Education, Inc. 2008.

1) A sample of college students was asked how much they spent monthly on a cell phone plan (to the nearest dollar).

 Monthly Cell Phone Plan Cost (\$) Number of Students 10 - 19 8 20 - 29 16 30 - 39 21 40 - 49 11 50 - 59 4

2) The following data represent the difference in scores between the winning and losing teams in a sample of 15 college football bowl games from 2004-2005.

 Point Difference Number of Bowl Games 1 - 5 8 6 - 10 0 11 - 15 2 16 - 20 3 21 - 25 1 26 - 30 0 31 - 35 1

3) The following table represents the distribution of the annual number of days over 100 degrees Fahrenheit for Dallas-Fort Worth for a sample of 80 years from 1905 to 2004.

 Days Above 100 Degrees Number of Years 0 - 9 25 10 - 19 33 20 - 29 14 30 - 39 5 40 - 49 2 50 - 59 1

4) The following table shows the distribution of the number of hours worked each week (on average) for a sample of 100 community college students.

 Hours Worked per Week Number of Students 0 - 9 24 10 - 19 14 20 - 29 39 30 - 39 18 40 - 49 5

5) The following data represents the age distribution of a sample of 100 people covered by health insurance (private or government). The sample was taken in 2003.

 Age Number 25 - 34 23 35 - 44 29 45 - 54 28 55 - 64 20

6) The following data represent the high temperature distribution in degrees Fahrenheit for a sample of 40 days from the month of August in Chicago since 1872.

 Temperature Days 60 - 69 3 70 - 79 15 80 - 89 17 90 - 99 5

7) The following data represent the annual rainfall distribution in St. Louis, Missouri, for a sample of 25 years from 1870 to 2004.

 Rainfall (inches) Number of Years 20 - 24 1 25 - 29 3 30 - 34 5 35 - 39 8 40 - 44 5 45 - 49 2 50 - 54 0 55 - 59 1

8) The following data represent the age distribution of a sample of 70 women having multiple-delivery births in 2002.

 Age Number 15 - 19 1 20 - 24 5 25 - 29 16 30 - 34 28 35 - 39 17 40 - 44 3