New SAT Math Workbook

In a problem such as this you can be sure that 6

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Unformatted text preview: lems, it is most important that you read carefully and know what it is that you are trying to find. Once this is done, represent your unknown algebraically. Write the equation that translates the words of the problem into the symbols of mathematics. Solve that equation by the techniques previously reviewed. Problem Solving in Algebra 173 1. COIN PROBLEMS In solving coin problems, it is best to change the value of all monies to cents before writing an equation. Thus, the number of nickels must be multiplied by 5 to give the value in cents, dimes by 10, quarters by 25, half dollars by 50, and dollars by 100. Example: Sue has $1.35, consisting of nickels and dimes. If she has 9 more nickels than dimes, how many nickels does she have? Solution: Let x = the number of dimes x + 9 = the number of nickels 10x = the value of dimes in cents 5x + 45 = the value of nickels in cents 135 = the value of money she has in cents 10x + 5x + 45 = 135 15x = 90 x=6 She has 6 dimes and 15 nickles. In a problem such as this, you can be sure that 6 would be among the multiple choice answers given. You must be sure to read carefully what you are asked to find and then continue until you have found the quantity sought. Exercise 1 Work out each problem. Circle the letter that appears before your answer. 1. Marie has $2.20 in dimes and quarters. If the 1 number of dimes is the number of quarters, 4 how many dimes does she have? (A) 2 (B) 4 (C) 6 (D) 8 (E) 10 Lisa has 45 coins that are worth a total of $3.50. If the coins are all nickels and dimes, how many more dimes than nickels does she have? (A) 5 (B) 10 (C) 15 (D) 20 (E) 25 A postal clerk sold 40 stamps for $5.40. Some were 10-cent stamps and some were 15-cent stamps. How many 10-cent stamps were there? (A) 10 (B) 12 (C) 20 (D) 24 (E) 28 4. Each of the 30 students in Homeroom 704 contributed either a nickel or a quarter to the Cancer Fund. If the total amount collected was $4.70, how many students contributed a nickel? (A) 10 (B) 12 (C) 14 (D) 16 (E) 18 I...
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