public async Task <CurrencyPair> GetAverageCurencyRateForDates(string firstCurrency, string secondCurrency, DateTime startDate, DateTime endDate) { CheckCurrences(firstCurrency, secondCurrency); var resultsCollection = await _apiProvider.GetCurrencyByDateRange(firstCurrency, secondCurrency, startDate, endDate); float average = resultsCollection.Select(x => x.ExchangeRate).Average(); return(new CurrencyPair(firstCurrency, secondCurrency, average, startDate, endDate)); }