For the baseball team's sports drink, one must use 6 gallons of water with 16 scoops of powder to yield a mixture that is 96% water (and 4% powder). Since initially there was 2 quarts of water, or 1/2 gallon of water, Daniel needs to add 5.5 extra gallons of water. The yield will be 100 cups (800 ounces) of sports drink.
Calculations: 16 scoops times 1/4 cup each = 4 cups of powder Since this is supposed to be 96% water, we need the powder to be only 4% of the total. If 4 cups is 4%, of the total, then 100 cups must be 100% of the total. So, we need 96 cups (or 96 * 8 = 768 ounces of water. Initially 64 ounces (2 quarts) of water were mixed with the 4 cups of powder. We need to add 768 - 64 or 704 ounces of water to complete the task. 704 ounces is 5.5 gallons since 1 gallon is 128 ounces.
Daniel needs to add 5 and one-half gallons of water to his mixture. The result will be 6.25 gallons of sports drink. Hopefully, that will be sufficient to keep his team hydrated. If the game goes extra innings (like the game between the San Francisco Giants and Washington Nationals on Saturday, October 4th, 2014, which lasted 18 innings) they may need to make some more.