Kuas Pitki: Economics - Elasticity Exercise Ex18 (經濟學

Saturday, October 25, 2014

習題 18 (p.63)：若阿榮在房租的支出永遠占其所得的 25%，則所得彈性 (elasticity) 為： (A) 0.25 (B) 1.00 (C) 2.50 (D) 25.0 。哪一選項為真？

答：(B) 1.00。

令 R = 房租支出金額，I = 所得金額；則，阿榮的所得彈性推導過程如下 ...

$\\ \\ \frac{R+\Delta R}{I+\Delta I}=\frac{R}{I}=0.25 \\ \\ \frac{I}{R}=\frac{1}{0.25}=4 \\ \\ R=0.25I \\ R+\Delta R=0.25I+0.25\Delta I \\ 0.25I+\Delta R=0.25I+0.25\Delta I \\ \\ \frac{\Delta R}{\Delta I}=0.25 \\ \\ \therefore E_{I}=\frac{\Delta R}{\Delta I}\times \frac{I}{R}=0.25\times 4=1 \\$

完

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Saturday, October 25, 2014

Economics - Elasticity Exercise Ex18 (經濟學 - 彈性, 習題 18)

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