Are the following statements normative or positive, or do they contain both normative and positive statements?

a. A higher income-tax rate would generate increased tax revenues. Those extra revenues should be used to give more government aid to the poor.

b. The study of physics is more valuable than the study of sociology, but both should be studied by all college students.

c. An increase in the price of corn will decrease the amount of corn purchased. However, it will increase the amount of wheat purchased.

d. A decrease in the price of butter will increase the amount of butter purchased, but that would be bad because it would increase Americans’ cholesterol levels.

e. The birth rate is reduced as economies urbanize, but it also leads to a decreased average age of developing countries’

populations.