# Question: What Rule Tells You How Long It Takes For A Country’s Income To Double?

The rule of 70 is used to estimate the number of years it would take for a certain variable to double.

Divide 70 by the variable’s growth rate to estimate the number of years it takes for the variable to double.

## How long will it take the economy to double in size?

For example, if an economy grows at 1 percent per year, it will take 70/1=70 years for the size of that economy to double. If an economy grows at 2 percent per year, it will take 70/2=35 years for the size of that economy to double.

## How do you know when a population will double?

Doubling time is the amount of time it takes for a given quantity to double in size or value at a constant growth rate. We can find the doubling time for a population undergoing exponential growth by using the Rule of 70. To do this, we divide 70 by the growth rate (r).

## What is the 7 year rule for investing?

The rule says that to find the number of years required to double your money at a given interest rate, you just divide the interest rate into 72. For example, if you want to know how long it will take to double your money at eight percent interest, divide 8 into 72 and get 9 years.

## What is the relationship between growth rate and doubling time?

Selected Answer: Growth rate is the increasing rate of the number of organisms in a population and doubling time is the amount of time it takes for a quantity to double in size or value. The relationship is that doubling time depends on growth rate. The formular is Dt= 70/r.

## How can I double my money in 5 years?

This is the number of years it will take for your money to double. For example, if your money is earning an 8 percent interest rate, you’ll double your money in 9 years (72 divided by 8 equals 9). Or, if your money is earning a 5 percent interest rate, you’ll double it in 14.4 years (72 divided by 5 equals 14.4).

## What is the 72 hour rule?

The 3-day rule, sometimes referred to as the 72-hour rule, requires all diagnostic or outpatient services rendered during the DRG payment window (the day of and three calendar days prior to the inpatient admission) to be bundled with the inpatient services for Medicare billing.