Answer
The result of (a) does not tell us anything about the median price in 2008.
Work Step by Step
The result of part (a) tells us about the average rate of change over a two-year period, which was negative.
Now, some combinations are possible. For example, during the first year, the median home price could have held steady, and then fell off in the second year (in 2008). Alternatively, it could have risen during 2007, and fell sharply in 2008 or it could have fallen during 2007, only to climb back during 2008.
So, the result of (a) does not tell us anything about the median price in 2008. To find out what really happened in 2008, we would graph $P(t)$, and find that there was a sharp decline during 2008.
