In an experiment at Virginia Tech, 20 northern oak seedlings were exposed to a fungus. Half of the seedlings received 368 ppm of nitrogen (treatment) during planting, and the other half received no nitrogen (control). The stem weights in grams, at the end of 140 days were recorded as follows :(Picture)Construct a 95% confidence interval for the difference in the mean stem weights between the treatment and control groups. Assume that the underlying populations are normally distributed with equal variances.

CILI W Treatment .32 .53 .28 .37 .47 .43 .36 .42 .38 .43 Control .26 .43 .47 .49 .52 .75 .79 .86 .62 .46