Mean, Mode, Median with Grouped Data

Find the mean, median and mode for this grouped data of test scores.

 Scores Frequency 65 2 70 3 75 2 80 5 85 8 90 7 95 5 100 3

 This problem could be solved by entering ALL 35 scores into one list, with the score 65 appearing twice, 70 appearing 3 times, and so on.  But if we deal with the data as we deal with a frequency histogram, we can accomplish our task more quickly. Enter the scores into L1 and the frequencies into L2. (See Basic Commands for entering data.) Find the Mean and Median: Method 1: (fast and easy) Press 2nd MODE (QUIT) to return to the home screen. Press 2nd STAT (LIST).  Arrow to the right to MATH. Choose option  #3: mean(  if you want the mean. Choose option  #4: median(  if you want the median. Your choice will appear on the home screen waiting for you to tell it which list to use.  This time we will tell the calculator the list containing the scores AND the list containing the frequencies.  Notice the comma separating the lists. Remember the List names appear on the face of the calculator above the number keys 1-6. Find the Mean and Median:   Method 2: (a bit more sophisticated) Press STAT.  Arrow to the right to CALC.   Now choose option #1: 1-Var Stats.  When 1-Var Stats appears on the home screen, tell the calculator the name of the list containing the scores AND the name of the list containing the frequency (such as:  1-Var Stats L1, L2) Press ENTER. Arrow up and down the screen to see the statistical information about the data. Find the Mode: The mode can be quickly determined by examining the chart to see which score occurred most often.  No calculator work needed. The mode is 85.