A and B went to market with 30 pigs each. A sold his pigs at 2 for $1, and B sold his pigs at the rate of 3 for $1, and they, together, received $25. The next day A went to market alone with 60 pigs, and, wishing to sell at the same rate, sold them 5 for $2, and received only $24. Why should he not receive as much as when B owned half of the pigs?

Answer. The rate of 2 pigs for $1 is 1 pig for $0.50, and the rate of 3 pigs for $1 is 1 pig for $0.33; the average rate is 2 pigs for $0.50 + $0.33, or $0.83 or 1 pig for $0.41. The rate of 5 pigs for $2 is 1 pig for $0.40. So it is seen that the reason A did not receive as much is that he sold his pigs at a less rate than when they both went to market.