Problem
17 There are 3 cinemas $\mathbf{A}, \mathbf{B}$ and $\mathbf{C}$. The mean number of seats per cinema is 380 There are 350 seats in cinema $\mathbf{A}$. There are 250 seats in cinema $\mathbf{B}$. Work out the number of seats in cinema $\mathbf{C}$.
Solution
Step 1 ：Total number of seats = Mean number of seats per cinema * Total number of cinemas = \(380 * 3 = 1140\)
Step 2 ：Number of seats in cinema C = Total number of seats - (Number of seats in cinema A + Number of seats in cinema B) = \(1140 - (350 + 250) = 540\)
Step 3 ：\(\boxed{540}\)
