Using the rule of 72, calculate the average annual growth rate of GDP needed for a country to double its size in just four years?

Which of the following is a true statement regarding the economic growth model's predictions and how it actually affects the real world?

A) The growth model predicts that poor countries will catch up with rich countries, but lower-income industrialized countries are not catching up to higher-income industrialized countries as a group. B) The growth model predicts that poor countries should catch up with rich countries, but developing countries are not catching up to lower-income industrialized countries as a group. C) The growth model predicts that poor countries will catch up with rich countries, and this is what we observe across all developmental categories of countries. D) The growth model predicts that poor countries will never catch up with rich countries, but lower-income industrialized countries are catching up to higher-income industrialized countries as a group.

Economists consider environmental pollution to be a(n)

a. externality. b. pure public good. c. allocatively efficient outcome. d. public interest outcome.