Suppose that John lent $2000 to a friend in 2010 and charges his friend a nominal interest rate of 15% (the loan is repaid in 2011). We measure John's real wealth in terms of one good: hotdogs. The price of each hotdog is $25 in 2010 and $30 in 2011. Which one of the following is closest to the exact real interest rate that John gets:
A) 4.16%
B) 5.0%
C) - 4.16%
D) -5.0%
E) 15%