Interest rate in USA is $3\%,$ interest rate in UK is $4\%,$ spot rate in US e $=$ $$/$pound $=1\mathrm{.}25,$ and the expected exchange rate after a year is e ex $=1\mathrm{.}21$

a$.$ Where is the opportunity for investment UK or US$?$

b$.$ What will be the gain for investor if she is investing $$1000000.$