4.27 Mark Cotteleer owns a company that manufactures sailboats. Actual demand for Marks sailboats during each season in 2006 through 2009 was as follows: Year Season 2006 2007 2008 2009 Winter 1,400 1,200 1,000 900 Spring 1,500 1,400 1,600 1,500 Summer 1,000 2,100 2,000 1,900 Fall 600 750 650 500 Mark has forecasted that annual demand for his sailboats in 2011 will equal 5,600 sailboats. Based on this data and the multiplicative seasonal model, what will the demand level be for Marks sailboats in the spring of 2011