Is there a ratio of ice to water when making ice water?Is there another way to make ice water?
In what context do you need ice water?
Generally, the ratio doesn't matter, the temperature of water with ice in it is always at its melting point, 0 degrees C (unless you just added the ice and the temperature is still going down).
No need to over analyze it. Just add enough ice to get the water cold. I've made the formula you are trying many times and there is no reason to drive yourself crazy. Have fun and good luck.