A bar tender replaces some quantity of alcohol having 40% concentration with water and thus the concentration of alcohol changes to 30%. If the alcohol which he replaced is mixed with another sample of 260 ml alcohol having 20% concentration, then a mixture having 27% concentration of alcohol is prepared. Find the initial quantity of alcohol having 40% concentration.
A bar tender replaces some quantity of alcohol having 40% concentration with water and thus the concentration of alcohol changes to 30%. If the alcohol which he replaced is mixed with another sample of 260 ml alcohol having 20% concentration, then a mixture having 27% concentration of alcohol is prepared. Find the initial quantity of alcohol having 40% concentration. Correct Answer 560 ml
Suppose the initial quantity of alcohol having 40% concentration is ‘x’ ml and the quantity replaced is y ml;
∴ 0.4(x – y) + 0 × y = 0.3x
⇒ 0.1x = 0.4y
⇒ x = 4y ---- (1)
Now he mixes ‘y’ ml alcohol having 40% concentration with 260 ml alcohol having 20% concentration,
And thus a mixture having 27% concentration of alcohol is prepared;
∴ y × 0.4 + 260 × 0.2 = (y + 260) × 0.27
⇒ 0.4y + 52 = 0.27y + 70.2
⇒ 0.13y = 18.2
⇒ y = 140
From equation (1)
x = 560 ml
∴ Initial quantity of alcohol having 40% concentration = 560 ml