In what ratio should water be mixed with some milk to gain 16$$\frac{2}{3}$$​% on selling it- at cost- price?

Correct option is D

Solution:

The price of water = 0
Profit = 16$$\frac23\%$$​​
Let the Quantity of milk be x
Quantity of water = a
Profit% = (Profit/C.P.) × 100%
=> (50/3)% = (a/x) × 100%
=> 50/300 = a/x
=> a/x = 1/6
=> a : x = 1 : 6