1. ## Percentage Change

On Sept 1, price of gas was $2.75/gallon,$3.25/gallon on Oct 1 and back down to $2.75/gallon on Nov 1. Express (a) and (b) answers in both dollar and percentage values. (c) in percentage points and (d) in percent. Between Sept 1 and Oct 1, price increased by _(a)__ . Between Oct 1 and Nov 1, price decreased by __(b)__ . On May 16 2000, the US federal reserve increased its target for the federal funds from 6.00% to 6.50%. This change of _(c)_ means that the Fed raised its target by approx _(d)_. (a)$0.50 or 18.18%
(b) \$0.50 or 15.38%
(c) 0.25 percentage points
(d) 8.33%

I'm helping my sister with her homework and I'm not sure if she expressed the percentages properly.

2. percent change $= \frac{present - prior}{prior} \times 100$

3. That is why, although the actual changes in (a) and (b) are the same, the percentage changes are different: what was "prior" is different so the while the numerators are the same the denominators are different.

The change for (c) is obviously 6.50- 6.00= 0.50 percentage points, not 0.25. What that a typo? Because (d) is correct and I don't see how you could get (d) with a wrong answer for (c)!