b) If a strong recovery raises national income from $4.0 trillion to $4.4 trillion and diamond sales jump from 3 million to 13 million carats annually, calculate the income elasticity of demand for diamonds.

c) If each 1 percent increase in the price of pencils causes a 2 percent decline in the quantity of erasers sold, the cross-price elasticity of demand for these goods is about _______ and the goods are ___________.

d) When John can sell totem poles for $1,800 each, he markets 60 annually. When the price falls to $600 each, he is willing to sell only 24 each year. What is his price elasticity of supply?