The average number of worms in a particular region is believed to have gone done over the last 20 years. The mean was believed to be 20 worms per cubic foot of soil. A study was done on 60 randomly selected cubic feet of soil and found 17 worms per cubic foot with a standard deviation of 2.6 worms per cubic foot. At an = .01 determine whether the number of worms per cubic feet of soil has decreased from 20.