document.write( "Question 1204890: A scientist has two solutions, which she has labeled Solution A and Solution B. Each contains salt. She knows that Solution A is 45% salt and Solution B is 95% salt. She wants to obtain 90 ounces of a mixture that is 65% salt. How many ounces of each solution should she use? \n" ); document.write( "
Algebra.Com's Answer #841425 by math_tutor2020(3817)\"\" \"About 
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\n" ); document.write( "Answers:
\n" ); document.write( "54 ounces of solution A
\n" ); document.write( "36 ounces of solution B\r
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\n" ); document.write( "\n" ); document.write( "Work Shown\r
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\n" ); document.write( "\n" ); document.write( "Method 1\r
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\n" ); document.write( "\n" ); document.write( "A+B = 90
\n" ); document.write( "B = 90-A
\n" ); document.write( "0.45A = amount of pure salt from solution A
\n" ); document.write( "0.95B = amount of pure salt from solution B
\n" ); document.write( "0.45A+0.95B = total amount of pure salt
\n" ); document.write( "0.45A+0.95B = 90*0.65
\n" ); document.write( "0.45A+0.95(90-A) = 58.5
\n" ); document.write( "0.45A+0.95*90+0.95*(-A) = 58.5
\n" ); document.write( "0.45A+85.5-0.95A = 58.5
\n" ); document.write( "-0.5A + 85.5 = 58.5
\n" ); document.write( "-0.5A = 58.5 - 85.5
\n" ); document.write( "-0.5A = -27
\n" ); document.write( "A = -27/(-0.5)
\n" ); document.write( "A = 54
\n" ); document.write( "B = 90-A = 90-54 = 36\r
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\n" ); document.write( "\n" ); document.write( "Method 2\r
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\n" ); document.write( "\n" ); document.write( "Solution A: 45%
\n" ); document.write( "Solution B: 95%
\n" ); document.write( "Target: 65%\r
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\n" ); document.write( "\n" ); document.write( "The gap from 45% to 65% is 20
\n" ); document.write( "The gap from 65% to 95% is 30
\n" ); document.write( "The ratio 20:30 reduces to 2:3\r
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\n" ); document.write( "\n" ); document.write( "We need 2 parts of one solution and 3 parts of another solution.
\n" ); document.write( "That scales up to 2x and 3x.
\n" ); document.write( "2x+3x = total amount of mixed solution
\n" ); document.write( "2x+3x = 90
\n" ); document.write( "5x = 90
\n" ); document.write( "x = 90/5
\n" ); document.write( "x = 18\r
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\n" ); document.write( "\n" ); document.write( "2x = 2*18 = 36
\n" ); document.write( "3x = 3*18 = 54
\n" ); document.write( "We know from method 1 which value goes where, but if we didn't have that luxury then we'd have to check each case.\r
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\n" ); document.write( "\n" ); document.write( "Case 1: We have 54 oz of A and 36 oz of B
\n" ); document.write( "Case 2: We have 36 oz of A and 54 oz of B\r
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\n" ); document.write( "\n" ); document.write( "Case 1 leads to 54*0.45 + 36*0.95 = 58.5 oz of pure salt, which matches with the result of 90*0.65 = 58.5
\n" ); document.write( "This confirms the answers found in method 1.\r
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\n" ); document.write( "\n" ); document.write( "Case 2 yields 36*0.45+54*0.95 = 67.5 oz of pure sault which doesn't match 90*0.65 = 58.5
\n" ); document.write( "We can eliminate this option.
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