Calculate the dollar rates of return on the following assets:
a. A painting whose price rises from $200,000 to $250,000 in a year.
b. A bottle of a rare Burgundy, Domaine de la Romanée-Conti 2011, whose price rises from $255 to $275 between 2013 and 2014.
c. A £10,000 deposit in a London bank in a year when the interest rate on pounds is 10 percent and the $/£ exchange rate moves from $1.50 per pound to $1.38 per pound.