Farina wrote:

QuantumWonder wrote:

First, note that the amount of phosphoric acid is 1.2L because it said 2 L at 60% concentration; hence 2(.6)=1.2

Next, we translate the sentence into an equation that is implicated on the amount of phosporic solution

2(.6) + 3x < .5(5)

1.2 + 3x < 2.5

x<.433

That means, 3 L of any solution with concentration less than .4333 works. Therefore A, B.

Next look at option F. Before doing that, note that the amount of phosphoric acid is NO more than 3(.4333) = 1.29 L

F. 2L of a 40% solution and 1L of a 45% solution

This means we have 2(.4) + .45(1) < 1.29 L of phosphoric acid, so F.

G. 1L of a 40% solution and 2L of a 45% solution

This means we have 1(.4) + .45(2) > 1.29 L of phosphoric acid so eliminate it.

So A, B, F

I think there is some problem with calculation of G. Plus as per your explanation x should be less than 43% so I am unable to understand your explanation with point F and G

You can consider the sum as:

60% of 2L + Extra < 50% of 5L

Therefore, 1.2 + y < 2.5

Now you just have to see that 1.2 + y

does not exceed and does not equate to 2.5, So

Option A: y = 40% of 3L = 1.2 (correct)

Option B: y = 42% of 3L = 1.26 (correct)

Option C: y = 44% of 3L = 1.32 (incorrect)

Option D: y = 46% of 3L = 1.38 (incorrect)

Option E: y = 48% of 3L = 1.44 (incorrect)

Option F: y = 40% of 2L + 45% of 1L = 1.25 (correct)

Option G: y = 40% of 1L + 45% of 2L = 1.3 (incorrect)