In order to get the percentage of humidity, we need to take the vapour mass \(V \)and divide it by the total air volume \(T\).
We know that \( T = 100 \) for each of the containers, and we also know that \( V_1 = V_2\) for the two containers and \( V_3\) is unknown.
To get the combined humidity, we divide the total vapour mass by the total air volume:
\(\frac{V_1 + V_2 + V_3 }{ 100 + 100 + 100} =\frac{ V_1 + V_2 + V_3 }{ 300} = 0.62\)
=> \(V_1 + V_2 + V_3 = 300 * 0.62 = 186\)
From here, let's say \(V_1 = V_2 = x \)
(as stipulated in the task) and\( V_3 = y\)
Therefore, we need to select such values from the anwer options that \(2x + y = 186\)
Let's start with the highest possible \(x \)of 65%:
\(65*2 = 130 = 186 - 56\)
[56 is not a suitable option]Then we try \(x\) of 64%:
\(64*2 = 128 = 186 - 58\)
[and 58 fits, well done!]Great! this lets us answer
that first two containers have 64% of humidity and
the third one has 58%.