Ben saves his pocket money as follows.
Each week he puts money into his piggy bank (which pays no interest). In the first week he puts in 10p. In the second week he puts in 12p. In the third week he puts in 14p, and so on.
How much money does Ben have in his piggy bank after 25 weeks?
On January 1st Shirley invests \(\pounds 500\) in a savings account that pays compound interest at \(3 \%\) per annum. She makes no further payments into this account. The interest is added on 31st December each year.
(a) Find the number of years after which her investment will first be worth more than \(\pounds 600\).
(b) State an assumption that you have made in answering part (ii)(a).