Jennie is making popcorn. The recipe calls for 1/2 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 to the nearest hundredth.

Jennie needs 1/2 cup of butter for 3 tablespoons of kernels.

She needs (1/2) / 3 = 1/6 cup of butter per tablespoon of kernels.
Thus, for 10 tablespoons of kernels, she needs 10 * (1/6) = <<10*(1/6)=1.6666666666666667>>1.67 cups of butter. Answer: \boxed{1.67}.