Practice set three, number five. Find the amount of interest a person can earn if he or she puts eighty dollars into

savings account that pays five percent simple interest for a length of four years. Use the formula

“I” equals “P” “R” “T”. “I” stands for the interest, amount that the person will earn. “P”

is the principal, the amount they put in. “R”, the interest

rate in simple interest entered as a decimal number. And “T”, the length of time in years. I need to

change my five percent simple interest into a decimal first. Recall that we pick

up our decimal point and move it two places to the left and then I do not include the percent symbol. So I’m ready for my formula. The interest

that I will earn is my principle, eighty dollars. Times my interest rate as a decimal, zero point zero five. Times my length of time, in four years. And I will use a calculator to help me

get the final answer. I have eighty times point zero five times four. And my final answer is: sixteen dollars of interest that this person will

earn.