Surface Ratio is the "Similarity Ratio" to the power of 2
Volume Ratio is the "Similarity Ratio" to the power of 3
It's logical and deductable by paying attention to the correlation between the "Side"s(or "Diameter"s) and the "Surface" and the "Volume"s in simple shapes like Circles and square.
By paying attention to the formula of the "Surface Area" and the "Volume" or the m /m^2 /m^3 ( the units of measurement) we can easily notice the relation.
17% of 400 is 68. Another way u can do it is 17% of 100 four times since its easier to do. 17% of 100 is 17. we have to do this 4 times since 100 goes into 400 four times. So 17*4 =68