Question
Elen operates two large cafes at two locations. The table below shows the number of staff working in these cafes.
| Waiters | Chefs/cooks | Cleaners | |
| Yum Cafe (Yishun) | 7 | 3 | 4 |
| Yum Cafe (Bishan) | 6 | 4 | 2 |
Their monthly salaries are made of a fixed base salary and fringe benefits. The table below shows the base salary and fringe benefits of each staff.
| Base salary | Fringe benefits | |
| Waiters | 2500 | 200 |
| Chefs/cooks | 3500 | 300 |
| Cleaners | 1500 | 80 |
It is given that the matrix P = 
and the matrix Q = 
.
(a) Evaluate the matrix R = PQ. [1]
(b) State what each element in R represents. [1]
(c) Elen increased the fringe benefits for each staff by 10%. Using the matrix R found in (a) and another matrix, find the new total monthly salary paid to all staff at each cafe.
Solution
