Regression analysis was used to estimate the following seasonal forecasting equation:
St = 124 + 18 D1 - 46 D2 - 28 D3 + 2.5 t
D1 is a dummy variable that is equal to one in the first quarter and zero otherwise; D2 is a dummy variable that is equal to one in the second quarter and zero otherwise; and D3 is a dummy variable that is equal to one in the third quarter and zero otherwise. Forecast the level of sales in the second quarter of time period ten (t = 10)