$80 in 1950 was worth $80 but in the year 2010 the same amount of money is...

Question:

$80 in 1950 was worth $80 but in the year 2010 the same amount of money is worth only $8.
a. What was the compounded average annual inflation rate (loss of purchasing power) during this period of time?
b. A hundred dollars invested in a bond in 1950 was worth $5,000 in 2010. In view of your answer to Part (a) what was the annual real interest rate earned on this investment?