To find the class midpoint Divide the class interval in half and add the result to the lower limit 16. Which of the following is not a guideline for a frequency distribution? Have more than 5 observations in each class 17. To convert a frequency distribution to a relative frequency distribution Divide the class frequency by the total number of observations 18. In a line chart the horizontal axis: Usually involves time, such as months or years 19. The difference between a histogram and a frequency polygon is The histogram employs bars whereas the midpoints are connected for a frequency polygon 20. In a cumulative frequency polygon We add the class frequencies starting with the first class 21. A difference between calculating the sample mean and the population mean is Only in the symbols, we use "X bar" instead of u and n instead of N. Where "X bar" means X with a bar on the top. 22