Question

In mixing a bug spray, a 40% solution of the chemical is mixed with an 85% solution to get 20 litres of a 60% solution. How much of each solution is required?

Answer 1

The amount of chemical in the 20 litres of the 60% solution is 20 * 0.6 = 12 litres.
Let A be the amount of 40% solution needed and let B be the amount of 85% solution needed. We can now write the following equation based on the amounts of chemical:
\[\large 12=0.4A+0.85B\ ............(1)\]
We know that the combined amounts of 40% and 85% solutions needed to make the final 60% solution must equal 20 litres. Therefore we can write:
\[\large A+B=20\ ........(2)\]
and rearranging (2) we get:
\[\large B=20-A\ .............(3)\]
Now we can plug the expression for B given in equation (3) into equation (1) to give:
\[\large 12=0.4A+0.85(20-A)\ .........(4)\]
Equation (4) can be simplified to give:
\[\large 0.45A=5\ ............(5)\]
Can you now solve equation (5) to find the value of A, and then substitute that value in equation (2) to find the value of B?

Answer 2

I must be really stupid, my mind isn't working and it doesn't make sense 1 can solve 5

Answer 3

can't

Answer 4

\[\large A=\frac{5}{0.45}=you\ can\ calculate\]

Answer 5

100/9 or 11.111111

Answer 6

b=20-100/9= 80/9 or 8.888888889

Answer 7

Yes, you are correct. the exact answers are:
\[\large A=11\frac{1}{9}\]
\[\large B=8\frac{8}{9}\]