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4 x 5 7200 x 4 x 36 000 5 x 9 x 36 000 x 4000 her

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Unformatted text preview: s .05(10,000 – x). (D) Let x = amount invested at 3% 2000 + x = her total investment .06 ( 2000 ) + .03x = .04 ( 2000 + x ) 6 ( 2000 ) + 3x = 4 ( 2000 + x ) 12, 000 + 3x = 8000 + 4 x 4000 = x Mark is now 8, so 2 years ago he was 6. 2. (D) Let x = Jack's age now x + 24 = Mr. Burke's age now x + 8 = Jack's age in 8 years x + 32 = Mr. Burke's age in 8 years x + 32 = 2 ( x + 8 ) x + 32 = 2 x + 16 16 = x Multiply by 100 to eliminate decimals. 4. (B) Let x = amount invested at 4% 7200 − x = amount invested at 5% .04 x = .05 ( 7200 - x ) Jack is now 16, Mr. Burke is 40. 3. (A) The fastest reasoning here is from the answers. Subtract each number from both ages, to see which results in Lili being twice as old as Melanie. 7 years ago, Lili was 16 and Melanie was 8. Let x = number of years ago Then 23 – x = 2(15 – x) 23 – x = 30 – 2x 7=x 4. (D) Karen’s age now can be found by subtracting 2 from her age 2 years from now. Her present age is 2x – 1. To find her age 2 years ago, subtract another 2. (D) Alice’s present age is 4x – 2. In 3 years her age will be 4x + 1. 5. Multiply by 100 to eliminate decimals. 4 x = 5 ( 7200 − x ) 4 x = 36, 000 − 5 x 9 x = 36, 000 x = 4000 Her income is .04(4000) + .05(3200). This is $160 + $160, or $320. (E) and In order to avoid fractions, represent his 1 his inheritance is 2x. 3 inheritance as 6x. Then 1 his inheritance is 3x 2 Let 3x = amount invested at 5% 2 x = amount invested at 6% x = amount invested at 3% .05(3x) + .06(2x) + .03(x) = 300 Multiply by 100 to eliminate decimals. 5 ( 3x ) + 6 ( 2 x ) + 3( x ) = 30, 000 15 x + 12 x + 3x = 30, 000 30 x = 30, 000 x = 1000 5. His inheritance was 6x, or $6000. www.petersons.com 192 Chapter 12 Exercise 5 1. (D) Represent the original fraction as 4x . 5x 4x + 4 2 = 5 x + 10 3 Exercise 6 1. (C) Multiply the number of pounds by the price per pound to get the total value. 40 ( x ) + 50 ( 30 − x ) = 40 x + 1500 − 50 x = 1500 − 10 x Cross multiply. 12 x + 12 = 10 x + 20 2x = 8 x=4 2....
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This note was uploaded on 08/15/2010 for the course MATH a4d4 taught by Professor Colon during the Spring '10 term at Embry-Riddle FL/AZ.

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