math
posted by jp .
The radiator in a car is filled with a solution of 70 per cent antifreeze and 30 per cent water. The manufacturer of the antifreeze suggests that for summer driving, optimal cooling of the engine is obtained with only 50 per cent antifreeze. If the capacity of the raditor is 4 liters, how much coolant (in liters) must be drained and replaced with pure water to reduce the antifreeze concentration to 50 per cent?

math 
Reiny
let's just look at the antifreeze,
right now the volume of antifreeze is .7(4) L or
2.8 L
Let the amount of the current fluid we are draining be x L
Now 70% of that is antifreeze, so the amount of antifreeze we lose is .7x
So the actual amount of antifreeze left in the rad
is 2.8  .7x L
But that be enough to produce our required 50% solution, if we pour in x L of straight water
2.8.7x + 0(x) = .5(4) > my equation only shows antifreeze
.7x = 22.8
.7x = .8
x = .8/.7 = 8/7 = appr 1.14 L 
math 
bobpursley
reduce by v, then the volume left if 4v
antifreeze conc*volume+solutionconc*volume=.5*4
1*v+.7(4v)=2
solve for v
Respond to this Question
Similar Questions

algebra help please
Mixture Problem... An auto tech needs a radiator to have a 40% antifreeze solution. The radiator currently is filled with 4 gallons of a 25% antifreeze solution. How much of the antifreeze mixture should be drained from the car if … 
algebra
A mechanic is working on a car that has a 10 Liter radiator that is currently filled with a mixture of water and antifreeze. thirty percent of the 10 liters is antifreeze and the rest is water. how much needs to be drained and replaced … 
math
The radiator in a car is filled with a solution of 70 per cent antifreeze and 30 per cent water. The manufacturer of the antifreeze suggests that for summer driving, optimal cooling of the engine is obtained with only 50 per cent antifreeze. … 
Algebra
The radiator in a car is filled with a solution of 75 per cent antifreeze and 25 per cent water. The manufacturer of the antifreeze suggests that for summer driving, optimal cooling of the engine is obtained with only 50 per cent antifreeze. … 
Math
The radiator in a car is filled with a solution of 60% antifreeze and 40% water. The manufacturer of the the antifreeze suggests that, for summer diving, optimal cooling of the engine is obtained with only 50% antifreeze. If the capacity … 
Math algebra
The radiator in a car is filled with a solution of 60% antifreeze and 40% water. The manufacturer of the the antifreeze suggests that, for summer diving, optimal cooling of the engine is obtained with only 50% antifreeze. If the capacity … 
math
At the end of Summer, Puss discovers that his radiator antifreeze solution has dropped below the safe level. If the radiator contains 4 gallons of a 25% antifreeze solution, how many gallons of pure antifreeze must he add to bring … 
math
At the end of Summer, Puss discovers that his radiator antifreeze solution has dropped below the safe level. If the radiator contains 4 gallons of a 25% antifreeze solution, how many gallons of pure antifreeze must he add to bring … 
math
A mechanic needs a radiator to have 40% antifreeze solution. The radiator currently is filled with 5 gallons of 15% antifreeze solution. How much antifreeze mixture should be drained from the car if the mechanic replaces it with pure … 
Math (Algebra II)
A mechanic says your radiator has only 40% antifreeze (the rest is water), but it needs to be 80% antifreeze. How much of the solution should be replaced with antifreeze?