Question

A mixture of 12 liters of chemical A, 16 liters of chemical B, and 26 liters of chemical C is required to kill a destructive crop insect. Commercial spray X contains 1, 2, and 2 parts, respectively, of these chemicals. Commercial spray Y contains only chemical C. Commercial spray Z contains only chemicals A and B in equal amounts. How much of each type of commercial spray is needed to get the desired mixture?

Answer 1

Answer:

• From Commercial spray X: 4 liters from Chemical A, 8 liters from Chemical B and 8 liters from Chemical C.
• From Commercial spray Y: 18 liters of Chemical C
• From Commercial spray Z: 8 liters of Chemical A and 8 liters of Chemical B.

Step-by-step explanation:

Since we need a lot of chemical C, we are going to leave Commercial spray Y   for last in case we lack in case we need more Chemical C, which is supplied by spray Y.

We need to cover the demand of both chemical A and B. For each liter of Chemical A we get 2 liters of Chemical B by using Commercial spray X. And for each liter of Chemical A we get 2 liters of Chemical B by using spray Z.

We will  call X the number of units of Commercial spray X used, where each unit contains 1 liter of Chemical A, 2 liters of Chemical B and 2 iters of Chemical C. Y is the number of units of Commercial spray Y used, containing each of them 1 liter of Chemical C, and Z the number of units of commercial spray Z used, on units containing both 1 liter of Chemical A and Chemical B.

We can represent the amount of liters we have for each chemical on a vector of the form (a,b,c) where a reresents the amount of Chemical A, b the amount of chemical B, and c the amount of chemical C. We want (a,b,c) to be equal to (12,16,26), in other words, we want a to be 12, b to be 16 and c to b 26. Furthermore we can obtain (a,b,c) by using this equation

(a,b,c) = X * (1,2,2) + Y * (0,0,1) + Z * (1,1,0) = (1*X+0*Y+1*Z,2*X+0*Y+1*Z,2*X+1*Y+0*Z) = (X+Z,2*X+Z,2*X+Y)

Thus, we have

• a = X+Z = 12
• b = 2*X+Z = 16
• c = 2*X+Y = 26

We can substract the second equation with the first one to obtain the value of X:

X = b-a = (2*X+Z)-(X+Z) = 16-12 = 4

Replacing X by 4, we obtain on the first expression that 4+Z = 12, hence, Z = 8. Since X is 4, 2*X+Y = 8+Y = 26. This gives us that Y must be 18.

We conclude that we need the following amount of Chemical A, B and C:

• From Commercial spray X: 4, 4*2 = 8 and 4*2 = 8 liters respectively
• From Commercial spray Y: 18 liters of Chemical C
• From Commercial spray Z: 8 liters of Chemical A and 8 liters of Chemical B.

I hope i could help you!