150 ml of 30% sulphuric acid was added to approximate 400 ml of 12% sulphuric acid solution. Find the approximate concentration W of the acid in the mixture?
Choose the correct choice from the following:
A) 1 / 2	B) 1 / 3	C) 1 / 4	D) 1 / 6	E) 1 / 5

Rationale: "do not need any computation 30 % - - - - - - - - - - - 21 % - - - - - - - - - 12 % if volume of both sol . were equal the concentration w would be 21 % = 1 / 5 , but 12 % is more than 3 times only possibility is 1 / 6 d"
Answer: D