150 ml of 30% sulphuric acid was added to approximate 400 ml of 12% sulphuric acid solution. Find the approximate concentration C of the acid in the mixture?  Choose the correct choice from the following answers.
A) 1/2
B) 1/3
C) 1/4
D) 1/6
E) 1/5
Do not need any computation   30%-----------21%---------12%   if volume of both sol. were equal the concentration C would be 21%=1/5, but 12% is more than 3 times   only possibility is 1/6   1/6
<result>D</result>
150 ml of 30% sulphuric acid was added to approximate 400 ml of 12% sulphuric acid solution. Find the approximate concentration C of the acid in the mixture?