How many gallons each of 15% alcohol and 10% alcohol should be mixed to obtain 5 gal of 11% alcohol?\begin{tabular}{|c|c|c|}\hline \begin{tabular}{c} Gallons of \\Solution\end{tabular} & \begin{tabular}{c} Percent \\(as a decimal)\end{tabular} & \begin{tabular}{c} Gallons of \\Pure \\Alcohol\end{tabular} \\\hlinex & 15%=0.15 & \\\hliney & 10%=0.1 & \\\hline 5 & 11%= & \\\hline\end{tabular}How many gallons of 15% alcohol should be in the mixture? □ gal
Q. How many gallons each of 15% alcohol and 10% alcohol should be mixed to obtain 5 gal of 11% alcohol?\begin{tabular}{|c|c|c|}\hline \begin{tabular}{c} Gallons of \\Solution\end{tabular} & \begin{tabular}{c} Percent \\(as a decimal)\end{tabular} & \begin{tabular}{c} Gallons of \\Pure \\Alcohol\end{tabular} \\\hlinex & 15%=0.15 & \\\hliney & 10%=0.1 & \\\hline 5 & 11%= & \\\hline\end{tabular}How many gallons of 15% alcohol should be in the mixture? □ gal
Define Variables: Let x be the gallons of 15% alcohol and y be the gallons of 10% alcohol. We know that x+y=5 because we want 5 gallons of the final mixture.
Calculate Total Alcohol: We also know that the amount of pure alcohol in the 15\% solution is 0.15x and in the 10\% solution is 0.1y. The final mixture has 11\% alcohol, so the total pure alcohol in the final mixture is 0.11×5.
Set Up Equation: Now we can set up the equation for the total pure alcohol: 0.15x+0.1y=0.11×5.
Substitute and Simplify: Substitute y with 5−x (from the first equation) into the alcohol equation: 0.15x+0.1(5−x)=0.55.
Combine Like Terms: Distribute the 0.1 into the parentheses: 0.15x+0.5−0.1x=0.55.
Isolate Variable: Combine like terms: 0.05x+0.5=0.55.
Solve for x: Subtract 0.5 from both sides: 0.05x=0.05.
Solve for x: Subtract 0.5 from both sides: 0.05x=0.05. Divide both sides by 0.05 to solve for x: x=0.050.05.
More problems from Weighted averages: word problems