A leading cell phone company forecasts that it will sell 3 million units

(Making Probability Statements from Forecasts)

A leading cell phone company forecasts that it will sell 3 million units next year of its best selling phone. In the past, actual sales have been unbiased with forecast errors having a standard deviation equal to 10 percent of forecasted sales. What are the chances that less than 2.5 million phones will be sold next year.