Lesson 108 & 109

Fractional Percents

Simple Interest

Compound Interest

Review

• How do I change a fraction into a percent?

• How do I change a decimal into a percent?

Review

• How do I change a decimal into a fraction?

• How do I change a percent into a fraction?

Example 108.1

• Write each percent as a decimal number:

• 4.2%

• 0.05%

• 4 ½%

• 3/20%

Example 108.2

• Four and one half percent of the students did not brush their teeth every day. If there were 1200 students in all, how many did not brush their teeth every day?

Example 108.3

• Complete the table:

Fraction Decimal Percent

0.04%

22 ½%

1/4 %

Simple Interest

• Money paid to you by the bank for putting your money into the bank

• Interest is a fixed percentage of the money you invest

• Simple interest is a fixed percentage of the original investment

• Credit cards are like this, you are charged a set amount of interest each month based on your balance

Example 109.1

• Jim put $5000 in the bank for 2 years at a 8 percent simple interest. How much money did he get when he withdrew his money after 2 years?

Example 109.2

• Maria deposited $800 at 8 percent simple interest. At the end of 3 years she will have how much money?

Compound Interest

• Interest that is added at certain intervals throughout the year– Can be monthly– semi-monthly– weekly– daily– Quarterly

• You need to refigure the amount each time the interest is compounded– Means that if it’s compounded weekly, you refigure the

percent by adding on the interest from the week before

Example 109.3

• How much will $700 be worth in 2 years if the money is deposited at 9 percent interest compounded annually?

Example 109.4

• How much would Elvira’s $7000 be worth in 2 years if it had been deposited at 9 percent interest compounded annually?