For each growth rate below, use the rule of 70 to calculate (i) how long it will take incomes to double, and (ii) if each country starts with an income of $1,000 per capita, what the income will be in 30 years.     

a. 4 percent.  

b. 7 percent.  

c. 2.5 percent.    

d. 10 percent.  

e.   3 percent.