The median sales prices for new single-family houses for the years $2004-2007$ are as follows (Census Bureau website, March 19,2009 ).$$\begin{array}{lc}
\text { Year } & \text { Price (\$1000s) } \\
2004 & 221.0 \\
2005 & 240.9 \\
2006 & 246.5 \\
2007 & 247.9
\end{array}$$
a. Use 2004 as the base year and develop a price index for new single-family homes over this four-year period.
b. Use 2005 as the base year and develop a price index for new single-family homes over this four-year period.