Convert the percentages of the sample into their decimal equivalents. For example, a pie chart is presented to show the relationship between the number of children of particular ages in a kindergarten class. Given information: the total sample is 20 students. four-year-olds comprise 10 percent of the total. Five-year-olds comprise 75 percent of the total and six-year-olds comprise 15 percent. Convert and note the percentage represented in each wedge to its decimal equivalent dividing each by 100. Ten percent is equal to 0.10. Seventy-five percent equals 0.75 and 15 percent equals 0.15.
Calculate the number students in each age group. This is done by multiplying the total sample (20) by the decimal equivalent for each pie wedge. To calculate the number of four-year-olds, multiply 20 times 0.1. Calculate the number of five-year-olds by multiplying 20 times 0.75. Calculate the number of six-year-olds by multiplying 20 times 0.15. To check your answer, add the percentages. The correct answer should be 100 percent.
Calculate the relationships between the quantities of students in each age group. To do this, you must compare only two values at a time. Example: The question asks you to state the percentage of students that are more than four years old. Add the number of five-year-olds to the number of six-year-olds to find the sum of students that are more than four years old. Divide the sum by the sample (20) to find the answer. If you have calculated correctly, the number of students greater than four-years-old is equal to the sum of given percentages of five- and 6-year-olds.
Calculate the ratio of the number of students in one group to that in another group. If you are comparing the number of four-year olds (two) to the number of six-year-olds (3), simply divide one quantity into the other. Calculate the relationship in both directions, switching the numerator and denominator. By dividing two by three you will find that the number of four-year-olds is 0.67 times, or 67 percent of the number of six-year-olds. By dividing three by two you will find that the number of six-year olds is 1.5 times, or 150 percent of, the number of four-year-olds.