When marginal cost is greater than average cost, an increase in output up arrow average cost. when marginal cost is less than average cost, an increase in output ▼ up arrow down arrow average cost.

Amanager of a store that sells and installs spas wants to prepare a forecast for january and june of next year. her forecasts are a combination of trend and seasonality. she uses the following equation to estimate the trend component of monthly demand: ft = 30+5t, where t = 1 in january of this year. seasonal relatives are 0.60 for january and 1.50 for june. what demands should she predict for january and june of next year