The maximum class frequency is 35.
The class corresponding to this frequency is 9 - 11.
So, the modal class is 9 - 11.
L (Lower limit of modal class) = 9
$$f_{1}$$ (frequency of the modal class) = 35
$$f_{0}$$ (frequency of the class preceding the modal
class) = 20
$$f_{2}$$ (frequency of the class succeeding the modal class) = 18
h (class size) = 2
Mode = $$L + \left ( \dfrac{f_{1} - f_{0}}{2f_{1} - f_{0} -
f_{2}} \right ) * h$$
= $$9 + \left ( \dfrac{35 - 20}{2 * 35 - 20 - 18} \right )
*2$$
= $$9 + 0.9375$$
= $$9.9375 \approx 9.95$$
Hence, the mode of supply of milk is 9.94 litres.