4 The monthly rental prices, \(
) x$, for 9 apartments in a certain city are listed and are summarised as follows.
$$\Sigma ( x - c ) = 1845 \quad \Sigma ( x - c ) ^ { 2 } = 477450$$
The mean monthly rental price is \(
) 2205$.
- Find the value of the constant \(c\).
- Find the variance of these values of \(x\).
- Another apartment is added to the list. The mean monthly rental price is now \(
) 2120.50$. Find the rental price of this additional apartment.