I take the mathematical approach. Versabond calls for 6 quarts of water for the whole 50 pound bag. I filled a Folgers' Classic Roast 39 oz can with vb and weighed it at 9 pounds on my antique farmer's scale. So 9 pounds is 18 percent of the 50 pound bag, so I needed 18% of the 6 quarts of water. There are 32 ounces in a quart, times 6 is 192 and 18 percent of that is 34.56 ounces and so that's how much water I used, more or less.
Now, to generalize, 34.56 is 3.84 times 9, so if you can figure out how many pounds of versabond you wanna mix, in pounds, multiply it by 3.84 and that's how many ounces of water you should add.
Now, if you don't happen to have a 39 ounce Folger's Classic Roast can handy, or an old scale, or if you're not using versabond, it gets complicated. The 39 oz can is your "big" can of coffee, but there's no standardization. A small can of coffee might be 11.5 oz or 13 oz and a big can could be more or less, I don't know. That's why ceramic tilers make the big bucks because they know what it's supposed to look like and what kinda trowel will stand up straight in it when it's just right. But, just use those math skills you learned in high school and you'll be all set.
I really don't know why you're looking at this when y'all should be answerin' MY QUESTIONS