#Percent Problems
Percent One Number is of AnotherStudents learn to find a percent of a number. For example, to find 65% of 40, first rewrite 65% as the decimal 0.65, and "of 40" means "times 40", so we have 0.65 x 40, which equals 26. So 65% of 40 is 26.
#Using Percent to Find a NumberStudents learn to find the percent one number is of another. For example, to answer the question "54 is what percent of 72?", read the question from left to right. "54 is" means "54 equals", "what percent" means "x", and "of 72" means "times 72". So the equation reads 54 = (x)(72), or 54 = 72x. Next, divide both sides of the equation by 72, to get 0.75 = x. Finally, since "x" means "what percent", change 0.75 to a percent by moving the decimal point two places to the right, to get 75%. So 54 is 75% of 72.
#Percent Increase or DecreaseStudents learn to answer problems in the following form: "8% of what number is 6?" Reading the question from left to right, "8%" means "0.08", "of what percent" means "times x", and "is 6" means "equals 6". So the equation reads (0.08)(x) = 6, or 0.08x = 6. Next, divide both sides of the equation by 0.08, to get x = 75. So 8% of 75 is 6.
#Percent Applications
DiscountStudents solve word problems using the "discount" formula, which states: original price x rate of discount = discount. Students also solve word problems using the "sale price" formula, which states: original price - discount = sale price. For example: A tennis racket marked at $110.50 is on sale at 20% off. What is the discount? What is the sale price? Students also solve word problems using the "rate of discount" formula, which is the same as the percent decrease formula: amount of change/ original number. For example: An old video game is marked down from $48 to $18. What is the rate of discount?
#Percent Applications
Sales TaxStudents solve word problems using the "sales tax" formula, which states: purchase price x sales tax rate = sales tax. Students also solve word problems using the "total price" formula, which states: purchase price + sales tax = total price. For example: The sales tax rate in Iowa City, Iowa, is 7%. How much sales tax is charged on a graphing calculator that costs $82? What is the total price?
Percent Applications
Interest
#Students solve word problems using the "interest" formula, which states: interest = principal x rate x time. For example: How much principal must be invested to earn $471 in 3 years at an interest rate of 10%?
কোন মন্তব্য নেই:
একটি মন্তব্য পোস্ট করুন