Q3: According to the market research firm iSuppli, Apple's marginal cost was $21.77 (in 2009) for an iPod Shuffle, $187.51 (2010) for a 16GB iPhone 4, and $229.35 (in 2010) for a non-3G 16GB iPad. These products retailed for $79, $600 (though customers pay much less if they sign up for a two-year contract with AT&T), and $499 respectively. If Apple is producing at the short-run profit maximizing level, what is the elasticity of demand for the iPod, iPhone 4, and iPad? Show all the steps. Make sure you derive any economic result you want to apply to answer this question.