public double GetInterestRate(Account account)
 {
     double interestRate = 0.025;
     double highInterestRate = interestRate + 0.005;
     int thresholdBalance = 50000;
     int thresholdDays = 365*5;
     bool isEligibleForHigherRate = account.GetAverageDailyBalance() > thresholdBalance
                                    && (DateTime.Now - account.CreatedDate).Days > thresholdDays;
     return isEligibleForHigherRate ? highInterestRate : interestRate;
 }