The ratio of acid and water in solutions A and B is 15 : 11 and 4 : 9, respectively. 6 litres of A is mixed with 4 litres of B. How much acid (in ml) should be added to 390 ml of the resulting solution so that the ratio of acid and water in it becomes 3 : 2?
Show answer & explanation
Correct answer: D
Explanation
The correct answer is option 4 i.e. 127.5.
A = 15 : 11
Total = 26
Acid in 6L = × 6000 = 3461.54
Water = 6000 - 3461.54 = 2538.46
B = 4 : 9
Total = 13
Acid in 4L = × 4000 = 1230.77
Water = 4000 - 1230.77 = 2769.23
Total Acid = 3461.54 + 1230.77 = 4692.31
Total Water = 2538.46 + 2769.23 = 5307.69
Total = 10000 ml
390 ml sample:
Acid = × 390 = 183
Water = 207
Let the quantity of acid added be x
=
⇒ 2(183 + x) = 621
⇒ 366 + 2x = 621
⇒ 2x = 255
⇒ x = 127.5