The accompanying table shows the price and yearly quantity of souvenir T-shirts demanded in the town of Crystal Lake according to the average income of the tourists visiting.

Quantity of T | Quantity of T

~shirts dema | -shirts dema nded when av | nded when av erage tourist | erage tourist tes Osh incomes $2 income is $3 0,000 0,000 a 3,000 5,000 5 2,400 4,200 6 1,600 3,000 7 800 1,800

a. Using the midpoint method, calculate the price elasticity of demand when the price of a T-shirt rises from $5 to $6 and the average tourist income is $20,000.

Also calculate it when the average tourist income is $30,000.

b. Using the midpoint method, calculate the income elasticity of demand when the price of a T-shirt is $4 and the average tourist income increases from $20,000 to $30,000. Also calculate it when the price is $7.