Allison needs 18 liters of 5% saline solution . she has a 1% solution available. how many liters of the 1% solution and how many liters of the 10%solution should she mid to make the 5% solution

10 litres of 1% solution and 8 litres of 10% solution

Step-by-step explanation:

Let vol of 1% solution = x

So vol of 10% solution = 18 - x

5% of 18 litres = 0.9

Equation formed is

x + (18 - x)10 = 0.9 * 100

x + 180 - 10x  = 90

-9x = 90 - 180

-9x = -90

 x = 10 litres

step-by-step explanation:

12: 00 p.m. to 7: 00 p.m. is a total of 7 hours.

4: 00 p.m. to 7: 00 p.m. is a total of 3 hours.

this means that from 4: 00 p.m to 7: 00 p.m. this represents 3/7 of what was lost from 12: 00 p.m. to 7: 00 p.m.

after knowing this, after doing 11,600 - 6,800 = 4,800

4,800 represents 3/7 of what was lost for 7 hours.

we then divide 4,800 by 3 which gets 1,600.

because we know that 1,600 represents 1/7 of how much water was lost, we just have to multiply by 7, which gets 11,200.   after adding 11,200 to how much water was left at 7: 00 p.m. which was 6,800. 11,200 + 6,800 = 18,000

this means that the pool originally had 18,000 gallons in the pool.

you can also check your work by doing 18,000 - 4(1600), which becomes           1800 - 6400 which gets you 11,600.