Percentage is a mathematical concept that appears very frequently in everyday life. You read that a merchant is offering a twenty percent discount on a selected group of items. The manufacturer of an article of clothing states that the material is sixtyfive percent dacron and thirty five percent polyester. Savings banks pay a five and one half percent interest rate annually on regular savings accounts. The state of Connecticut has raised the rate of its sales tax to seven and one half percent.
These and similar items which appear daily in newspapers indicate the importance of understanding the concept of percentage. In order to live more insightfully, wisely and enjoyably every citizen should be able to perform simple mathematical calculations which enable him to compute discount and sales tax on purchases, gratuities for services performed, interest on savings accounts and loans, deductions from his weekly pay and other consumer related problems which he encounters from day to day.
Although percentage has been taught through the years in a variety of ways, many people do not understand the concept and do not know how to use it. When specific problems are assigned to be solved in a class, often students remark, “I do not know how to begin. What shall I do first? Shall I multiply or shall I divide? Shall I use the formula B x R = P, or P Ö B, or PÖ B= R?”
In this unit of study we will try to improve the students’ understanding of percentage by providing them with a consistent and meaningful method of solution for general problems. After reviewing the fundamental arithmetic skills involved in percentage, the students will apply them to significant problems faced by the consumer in his daily affairs.
There are several basic objectives for this unit of study. Upon completion of it, the student will be able to:
— understand the meaning of percentage. change any percent to its equivalent decimal or fractional form. find a percentage of a given number.
— find what rate of percent one number is of another.
— find a number when a percentage of it is given.
— find the rate of percent greater or smaller one number is than another.
— solve consumer related problems by using percentage.
The material developed here may be used at several levels of instruction for the following purposes: (1) to introduce the concept of percentage and its applications to middle school students who have not been exposed to the topic previously, (2) to improve the skills of high school students who have not mastered the techniques adequately, (3) to serve as remedial work in adult basic education classes.