. Plastic grocery bags have almost replaced brown bags. When the plastic bags were introduced, problems with tearing and ripping resulted in disturbed customers. One company was trying to increase the tensile strength of the bags. The following statistics were obtained from two independent random samples and give the tensile strengths of plastic bags from two different production runs. Obtain a 90% confidence interval for difference between two means. Interpret the result in terms of the problem. Run 1 Run 2 Sample size 32 40 Mean 102.33 118.19 S. d. 14.06 24.44