Cake of Soap If you place 1 cake of soap on a pan of a scale and 3⁄4 cake of soap and a 3⁄4 pound weight on the other, the pans balance. How much does a cake of soap weigh? Answer 3 pounds. Since 1⁄4 cake weighs 3⁄4 pound, an entire cake weighs 3 pounds. « Previous RiddleSaving Time Next Riddle »Weather Forecast