convert the percentage to a decimal then multiply by 6,600. To get the number of people of 100%, divide 1.25 (the percent of 6,600) by 6,600. That should be right,
You use pi times radius squared. Pi 15 squared=706.858 then take 706.858 and multiply it by the depth of 12. 706.858×12=8482.3 Cm squared. 8482.3 cm to liters is about 8.5 liters