Answer
By real money, i assume you mean money that is guaranteed to keep its value as prices rise due to inflation. in contrast, fiat money does not have this feature -- inflation erodes away the value of nominal money.so, clearly, if you are going to hold money for longer than 30 seconds, it would be better to hold real money than nominal money, because its value will be the same 1 day from now or 30 days from now or 10 years from now.