2. A food scientist developed a nutritional supplement that was designed to improve weight gain. A
sample of 21 individuals were told to follow a certain diet that included the supplement. A
sample of 27 other individuals followed the same diet but without the supplement. After 10
weeks a 90% confidence interval for the difference of mean weight gain was computed to be
(-1.3, 2.1) pounds. Explain what one can conclude from this confidence interval. In particular,
can one believe there is a difference in mean weight gain between the supplement and no
supplement?