Question

21.
A laboratory has a tank containing 500 gallons of 60% salt solution in water. On heating it, water
starts evaporating. How much water should evaporate such that the resultant solution contains 75%
salt?​

Answer 1

Answer:

75 gallons

Step-by-step explanation:

initially

100%=500 gallons

60% of 500 is salt=300 gallons

remaining (100-60)%=40% of 500 is water=200 gallons

RESULTANT SOLUTION HAS 75% of salt solution =75% of 500=375 gallons

so remaining (500-375)=125 gallons

evaporated water =(initial water) -(resultant water)

=200-125=75 gallons

Answer 2

Answer:

100 gallons

Step-by-step explanation:

60% of 500 gallons is salt. Hence, 40% will be water.

So, (40/100)*500 = 200 gallons of water

Resultant salt concentration is 75% of (500 - x). Hence, water concentration is 25% of (500 - x). Here x being the amount of water evaporated.

Therefore we have,

200 - x = (25/100)*(500-x)

Upon solving,

x = 100 gallons