document.write( "Question 1113748: A box contains $7.15 in nickels, dimes, and quarters. There are 41 coins in all, and the sum of the numbers of nickels and dimes is 3 less than the number of quarters. How many coins of each kind are there? \n" ); document.write( "
Algebra.Com's Answer #728837 by greenestamps(13200)![]() ![]() You can put this solution on YOUR website! \n" ); document.write( "Tutor ikleyn's solution is a perfectly good solution using formal algebra. \n" ); document.write( "Here is a solution that is basically the same, but using logical reasoning instead of the formal algebra. \n" ); document.write( "There are 41 coins in all; the number of nickels and dimes together is 3 less than the number of quarters. So temporarily remove the 3 \"extra\" quarters, leaving a total of 38 coins, of which half are quarters. That means 19 quarters, and a total of 19 nickels and dimes. Then put back the 3 quarters; the number of quarters in the box is 19+3 = 22. \n" ); document.write( "The 22 quarters have a value of $5.50; so the total value of the 19 dimes and nickels is $7.15-$5.50 = $1.65. \n" ); document.write( "If all 19 of the remaining coins were dimes, the total value would be $1.90; but it is $1.65, which is 25 cents less than $1.90. Replacing a dime with a nickel keeps the same total number of coins but reduces the total value by 5 cents. Since all dimes gives us 25 cents more than we want, the number of times we need to replace a dime with a nickel is 25/5 = 5. \n" ); document.write( "So the number of nickels is 5, and the number if dimes is 19-5 = 14. \n" ); document.write( "Answer: 22 quarters, 14 dimes, 5 nickels. \n" ); document.write( "Check: 22(25)+14(10)+5(5) = 550+140+25 = 715 \n" ); document.write( " |