How much "stronger" is a drink with 100 proof alcohol than one with 80 proof alcohol?
My friend and I disagree about how to compute the difference between two drinks, one with 100 proof vodka and one with 80 proof. By volume the difference is 10% (40% vs 50% by volume), but in reality, isn't the one with 50% by volume 25% stronger than the one with 40% by volume?
In other words, how would this be answered:
The drink with 100 proof alcohol is ______ (% here) stronger than the drink with 80 proof alcohol.