Problem 1128. Simple return on investment

Assume you have some money and want to invest all your money to stock market. You randomly select a stock and invest all your money to that stock at time t. After n days you sell all your stocks from t+n price. What is your return in percent? Round results to two decimal places.

Take as an example, the closing prices of stock X;

 closing_prices = [721;702;703;698;692;705;714;729;735;750];

 return = (price(t+n)-price(t))/price(t) = (750-721)/721 = 4.02%

It is also assumed that you operate with closing prices!