The initial amount of the money is £11,000 and the interest is 3.9% per year for first 3 years and then 4.5% after that. If Dan invests it for 7 years, that means the interest would be 3 years of 3.9% and 4 years of 4.5%. The calculation would be:
total money= initial amount * interestrate1 * interest 2 total money= £11000 *(100%+3.9%)^3<span>*(100%+4.5%)^4 </span>total money= £11000 *(103.9%)^3 * (104.5%)^4 total money= £11000 * <span>1.121622319 </span>* 1.1925186 total money= £14,713.11