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;
}