A car radiator contains 10 liters of a 30 antifreeze solutio

A car radiator contains 10 liters of a 30% antifreeze solution. How many liters will have to be replaced with pure antifreeze so that the resulting solution is 50% antifreeze? In October, a greeting card company\'s profit was 12% more than it was in September. If the total profit for the two months was $689,000, find the profit for each month.

Solution

6.

solution = 10L

antifreeze agent = 10L * 30% = 3L

When xL of antifreeze is added, it should contain 50% antifreeze

(3+x)/ (10+x) = 0.5

3+x = 5 + 0.5x

0.5x = 2

x = 4L

so 4L pure antifreeze needs to be added

7.

Sept profit + oct profit = 689000

Let sept profit be s, so oct profit = 1.12s

so

s+1.12s = 689,000

2.12 s = 689,000

s = 689,000/2.12 = 325,000

sept profit = 325,000

oct profit = 325,000 * 1.12 = 364,000