Jennie is making popcorn. The recipe calls for 12 cup of butter, 3 tablespoons of kernels, and 1 teaspoon of salt. If she uses 10 tablespoons of kernels, how much butter does she need? Round your answer to the nearest hundredth.
Since the ratio of butter to kernels is 12 cups / 3 tablespoons, we need to divide 12 cups by 3 tablespoons to find the conversion factor: 12 cups / 3 tablespoons = 4 cups per tablespoon
Then we take the number of tablespoons Jennie used, multiply it by the conversion factor, and round to the nearest hundredth: 10 tablespoons * 4 cups/tablespoon = <<10*4=40>>40 cups
So Jennie needs 40 cups of butter.