4 Sam starts a job with an annual salary of \(\pounds 16000\). It is promised that the salary will go up by the same amount every year. In the second year Sam is paid \(\pounds 17200\).
- Find Sam's salary in the tenth year.
- Find the number of complete years needed for Sam's total salary to first exceed \(\pounds 500000\).
- Comment on how realistic this model may be in the long term.