In the past six months, Luke's take-home income increased from $4,000 per month to $5,000 per month. While on vacation in Hawaii, Luke told his wife to buy whatever jewelry she would like, as the jewelry was rare to find off the island. Normally his wife would buy one jewelry item while on vacation. However, this time she purchased four jewelry items. Using the mid-point formula, the income elasticity is and the jewelry items are goods.