1. On Jim's 11 th birthday his parents invest \(\pounds 1000\) for him in a savings account.

The account earns 2\% interest each year.
On each subsequent birthday, Jim's parents add another \(\pounds 500\) to this savings account.
Let \(U _ { n }\) be the amount of money that Jim has in his savings account \(n\) years after his 11th birthday, once the interest for the previous year has been paid and the \(\pounds 500\) has been added.

1. Explain, in the context of the problem, why the amount of money that Jim has in his savings account can be modelled by the recurrence relation of the form $$U _ { n } = 1.02 U _ { n - 1 } + 500 \quad U _ { 0 } = 1000 \quad n \in \mathbb { Z } ^ { + }$$
2. State an assumption that must be made for this model to be valid.
3. Solve the recurrence relation $$U _ { n } = 1.02 U _ { n - 1 } + 500 \quad U _ { 0 } = 1000 \quad n \in \mathbb { Z } ^ { + }$$ Jim hopes to be able to buy a car on his 18th birthday.
4. Use the answer to part (c) to find out whether Jim will have enough money in his savings account to buy a car that costs \(\pounds 4500\)