Correct Answer - Option 2 : 2 : 3
Let volume of alcohol solutions are V1 and V2 respectively.
⇒ Volume of alcohol in the resulting mixture = 15% of V1 + 20% of V2
⇒ ((15/100) × V1) + ((20/100) × V2)
⇒ (15V1+ 20V2 )/100
which is also equal to 18% of (V1 + V2).
⇒ (15V1+ 20V2 )/100 = (18 × (V1 + V2))/100
⇒ 2V2 = 3V1
The ratio of volume is 2 : 3 .
If a mixture of Q1 quantity C1% content is mixing with Q2 quantity C2% mixture, and the concentration of the new mixture is Cnew% , then the following equation can be used
C1% of Q1 + C2% of Q2 = Cnew% of (Q1 + Q2)
⇒ C1Q1 + C2Q2 = Cnew(Q1 + Q2)