8.13 A problem of considerable import to the small-scale farmer who purchases young pigs to fatten and sell for slaughter is whether there is any difference in weight gain for male and female pigs when the two genders are subjected to identical feeding treatments. If there is a difference, the farmer can optimize production by buying only one gender of pigs for fattening. As a public service, an agricultural experiment station decides to run a controlled experiment to determine whether gender is an important factor in weight gain. They placed eight young male pigs in one pen and eight young females in another pen and gave each pen identical feeding treatments for a fixed period of time. The initial weights were all between 35 and 50 1b, and the amounts of weight gain in pounds for the two genders are recorded below. One of the female pigs died so there are only seven observations in that group. Analyze the data below using both a test and a confidence-
interval approach with confidence coefficient near 0.90.
Female pigs: 9.31, 9.57, 10.21, 8.86, 8.52, 10.53, 9.21 Male pigs: 9.14, 9.98, 8.46, 8.93, 10.14, 10.17, 11.04, 9.43