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The cooling system of Alex's car holds 10 quarts. It is now filled with a mixture that is 60% water and 40% antifreeze. Hearing a weather forecast for severe cold, Alex decides to increase the strenth of the antifreeze mixture to 50%. To do this, Alex must drain off a certain number of quarts from the cooling system and then replace them by pure antifreeze. How many quarts must be drained?

 Jun 18, 2021

Best Answer 

 #1
avatar+33360 
+2

Alex needs 10 quarts of 50%      ....so he needs  5 quarts of antifreeze  and 5 qts water

 

he currently has only   4 quarts antifreeze   and 6 quarts of water

 

....a 40% solution

 

.40 (x)   +   1 (10-x)   =  .50 (10)

.40x + 10 -x = 5

-.6x = -5

x = 5/.6 = 8.333 quarts  of   40%    will be needed to start    then 1.67 quarts of pure antifreeze will be added

 

10 - 8.33 = 1.67 quarts to drain and refill with 100% a-freeze

 Jun 18, 2021
 #1
avatar+33360 
+2
Best Answer

Alex needs 10 quarts of 50%      ....so he needs  5 quarts of antifreeze  and 5 qts water

 

he currently has only   4 quarts antifreeze   and 6 quarts of water

 

....a 40% solution

 

.40 (x)   +   1 (10-x)   =  .50 (10)

.40x + 10 -x = 5

-.6x = -5

x = 5/.6 = 8.333 quarts  of   40%    will be needed to start    then 1.67 quarts of pure antifreeze will be added

 

10 - 8.33 = 1.67 quarts to drain and refill with 100% a-freeze

ElectricPavlov Jun 18, 2021

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