| Date | May 2013 | Marks available | 3 | Reference code | 13M.1.sl.TZ1.14 |
| Level | SL only | Paper | 1 | Time zone | TZ1 |
| Command term | Find | Question number | 14 | Adapted from | N/A |
Question
Jenny invested $20 000 in a bank account that paid 3.5 % annual simple interest. She withdrew her investment from the account when its value was $31 200.
Ramón invests $18 000 in a bank account that pays 3.4 % nominal annual interest, compounded quarterly.
Find the minimum number of years that Ramón must invest the money for his investment to be worth $27 000.
Markscheme
\(27000 = 18000{\left[ {1 + \frac{{3.4}}{{100 \times 4}}} \right]^{4n}}\) (M1)(A1)
Note: Award (M1) for substituted compound interest formula, (A1) for correct substitutions.
\((n =) 12\) (A1) (C3)
Note: Correct answer only. If 11.976… seen award (A2).
Examiners report
Although this question was late in the paper there were a number of candidates who scored fullmarks. Others were able to do simple interest but not compound interest or vice versa. However there were a large number that scored zero.
