Quantitative Aptitude Test Question 10

by Kalpana
(Chennai)

Quantitative Aptitude Test Question 10 seems to be wrong for me. Because in the question they half asked to add water in order to make the water milk ratio 1:1(if my understanding is correct)

But the answer is provided for the ration 7:3.

Can anybody clarify my question.

Thanks,
Kalpana