cost of $40 each and sells each coat for $70. Any coats unsold at the end of December are marked down to $30 and sold in a special New Year's clearance sale. Any unsold coats always sell during the clearance sale. The fallowing is the number of sales of coats for the past 10 years: 80, 100, 80, 110, 60, 90, 80, 80, 70, 90.Determine the critical ratio.
Fig: 1