An ammonia and water mixture fills a five-gallon container. Eighty percent of the mixture is ammonia but some of the mixture will be drained and replaced with pure water. If a five gallon mixture of sixty percent ammonia is desired, how many quarts of the mixture need to be drained before the water is added? (A quart is onefourth of a gallon.)

Guest Jun 29, 2022

#1**+1 **

4 galllons of the current mixture is ammonia (80% of 5)

We need 3 gallons of ammonia at the end

Let x be the number of gallons drained off and.8x the amount of ammonia drained off

(4 - .8x) = .6 *5

4 - .8x = 3

4 - 3 = .8x

1 = .8x

1/.8 = x = 1.25

We need to drian off 1.25 gal

Proof

4 gallons of ammmonia to start with

When we drain away 1.25 gallons, 80% of this is ammonia.....so 4 - .8(1.25) = 3 gallons of ammonia are left

Adding back 1.25 gallons of pure water = 5 gallons and 3 of this is ammonia...so....3/5= .60 = 60%

And 1.25 gallons = 5 qts

CPhill Jun 29, 2022