Math is also presented through Percent Applications in this unit. Lessons include percent, discount and sale price, simple interest, commission, sales tax and percent change. Real-life money problems are used throughout this unit.
Concepts: percent, fraction, decimal, discount, tax, interest
DISCOUNT
Stores often sell goods for a discounted price. Typically, a store will discount an item by a percent of the original price. The rate of discount is usually given as a percent, but may also be given as a fraction. The phrases used for discounted items include, " off," "Save 50%," and "Get a 20% discount."
Procedure:
- To calculate the discount, multiply the rate by the original price.
- To calculate the sale price, subtract the discount from original price.
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INTEREST
Interest is the amount of money the lender is paid for the use of his/her money. Interest is the money you pay to use someone else's money. In either case, the more money being used and the longer it is used for, the more interest must be paid. So whether you are borrowing or lending (investing) money, interest is found by taking the product of the principal, the interest rate and the time in years. The formula for finding simple interest is: Interest = Principal * Rate * Time which is also written as I = P*R*T
Read more at: http://www.mathgoodies.com/lessons/percent/interest.html
TAX
Sales tax is a tax on goods and services purchased and is normally a percentage added to the buyer's cost.
Read more at http://www.mathgoodies.com/lessons/percent/sales_tax.html
Assessment:
Create math stories (some kind of word problems with more details) based on your experience dealing with discount, tax and interest. Try to solve the problems. You can put some evidence (the bills, the brochure or bank notes) on to your math stories.
Example of one of Math stories:
Story:
My family came to the USA for a holiday visit. After purchasing $32.00 in clothing at a department store, I was presented with a bill for $34.36. Why did the department store charge him the additional $2.36? How did the department store compute this amount? What amount should Mr. Smith pay?
Analysis:
The department store was adding sales tax to the bill. Sales tax is a tax on goods and services purchased and is normally a certain percentage added to the buyer's cost.
Solution:
2.36 ÷ $32.00 = 0.0735.
Sales tax was charged by the department store at a rate of 7.375%.
Answer:
Mr. Smith should pay the department store $32.00 plus $2.36 in sales tax for a total bill of $34.36.