# Estimating Economic Growth

The answer is 238.64%. A good way of approximating is to use the rule of 70. If x is the growth rate then the doubling time is approximately 70/x. Thus, with a growth rate of 5% we expect a doubling (100% increase) in 14 years and a quadrupling in 28 years so a bit more than a tripling in 25 years (200% increase) is a good guess.