The rust mite, a major pest of citrus in Florida, punctures the cells of leaves and fruit. Damage by rust mites is readily recognizable because the injured fruit displays a brownish (rust) color and is somewhat reduced in size depending on the severity of the attack. If the rust mites are not controlled, the affected groves have a substantial reduction in both the fruit yield and the fruit quality. In either case, the citrus grower suffers financially because the produce is of a lower grade and sells for less on the fresh-fruit market. This year, more and more citrus growers have gone to a program of preventive maintenance spraying for rust mites. In evaluating the effectiveness of the program, a random sample of sixty 10-acre plots, one plot from each of 60 groves, is selected. These show an average yield of 850 boxes of fruit, with a standard deviation of 100 boxes. Give a 95% confidence interval for m, the average (10-acre) yield for all groves utilizing such a maintenance spraying program. Assume that s can be replaced by s.