This Math quiz is called 'Consumer Math (Calculating Compound Interest to the Whole Dollar)' and it has been written by teachers to help you if you are studying the subject at middle school. Playing educational quizzes is a fabulous way to learn if you are in the 6th, 7th or 8th grade - aged 11 to 14.
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Do you remember what “interest” is in the monetary world of saving and borrowing? Interest is the amount of extra money you earn or you have to pay back. On savings, you earn, while on loans and credit, such as credit cards, you pay back. Both are paid on the base value of what was saved or loaned. This base value is known as the principal.
Okay, let’s tackle the next ten problems. For each problem find out how much compound interest will need to be paid or earned and how much in total will be paid back or will be in savings. (Round decimals to the nearest 100th.)
280(1 + .056)3
(1 + .056)3 = (1.056 x 1.056 x 1.056) = 1.1775836 rounded to 1.18 (Remember that since the time number (i.e., 3 years here) is placed to the 3rd power [or cubed] we multiply the number by itself 3 times. We do not multiply 1.056 x 3.)
280 x 1.18 = $330.40 (is the amount in savings after 3 years)
$330.40 - $280.00 = $50.40 (is the compound interest earned over 3 years)
Solution: Penny will earn $50.40 in compound interest and her savings in 3 years will be $330.40.
Answer (c) is the correct answer