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Unformatted text preview: from his present age. Example: Michelle was 15 years old y years ago. Represent her age x years from now. Solution: Her present age is 15 + y. In x years, her age will be her present age plus x, or 15 + y + x. Example: Jody is now 20 years old and her brother, Glenn, is 14. How many years ago was Jody three times as old as Glenn was then? Solution: We are comparing their ages x years ago. At that time, Jody’s age (20 – x) was three times Glenn’s age (14 – x). This can be stated as the equation 20 – x = 3(14 – x) 20 – x = 42 – 3x 2x = 22 x = 11 To check, find their ages 11 years ago. Jody was 9 while Glenn was 3. Therefore, Jody was three times as old as Glenn was then. Exercise 3
Work out each problem. Circle the letter that appears before your answer. 1. Mark is now 4 times as old as his brother Stephen. In 1 year Mark will be 3 times as old as Stephen will be then. How old was Mark two years ago? (A) 2 (B) 3 (C) 6 (D) 8 (E) 9 Mr. Burke is 24 years older than his son Jack. In 8 years, Mr. Burke will be twice as old as Jack will be then. How old is Mr. Burke now? (A) 16 (B) 24 (C) 32 (D) 40 (E) 48 3. Lili is 23 years old and Melanie is 15 years old. How many years ago was Lili twice as old as Melanie? (A) 7 (B) 16 (C) 9 (D) 5 (E) 8 Two years from now, Karen’s age will be 2x + 1. Represent her age two years ago. (A) 2x – 4 (B) 2x – 1 (C) 2x + 3 (D) 2x – 3 (E) 2x – 2 Alice is now 5 years younger than her brother Robert, whose age is 4x + 3. Represent her age 3 years from now. (A) 4x – 5 (B) 4x – 2 (C) 4x (D) 4x + 1 (E) 4x – 1 4. 2. 5. www.petersons.com 176 Chapter 12 4. INVESTMENT PROBLEMS
All interest referred to is simple interest. The annual amount of interest paid on an investment is found by multiplying the amount invested, called the principal, by the percent of interest, called the rate. PRINCIPAL · RATE = INTEREST INCOME Example: Mrs. Friedman invested some money in a bank paying 4% interest annually and a second amount, $500 less than...
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- Spring '10