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George takes out a loan that gathers compound interest.

The table below shows the value of the loan over time.
a) What is the rate of interest per annum?
Give your answer as a percentage to 1 d.p.
b) Work out the value of the loan 10 years after it starts.
Give your answer in pounds (£) to the nearest 1p.
Start
After 1 year
After 2 years
£7500.00
£7905.00
£8331.87

User Brianoh
by
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1 Answer

3 votes

Final answer:

The annual interest rate on George's loan is determined to be 5.4%, calculated from the given values using the compound interest formula. The value of the loan after 10 years, using the same compound interest rate, is approximately £12,974.64, rounded to the nearest penny.

Step-by-step explanation:

To answer the student's questions about the compound interest on George's loan, we first need to determine the annual interest rate and then calculate the future value of the loan after 10 years.

Part a) Determining the Annual Interest Rate

Given the year-over-year increase in the loan amount, we can use the formula for compound interest, which is:


A = P(1 + r)^n

Where:
A = Final amount
P = Initial principal balance (= £7,500)
r = Annual interest rate
n = Number of times the interest is compounded per year

From the table, we have:
Year 1: £7,500 becomes £7,905
Year 2: £7,905 becomes £8,331.87

The interest rate can be found using the following steps:

  1. Calculate the interest factor for each year by dividing the final amount by the initial principal:
  2. Year 1: £7,905 / £7,500 = 1.054
  3. Year 2: £8,331.87 / £7,905 = 1.054
  4. Find the nth root of the interest factor where n equals the number of years, which in this case is 1, giving us the interest rate for one year.
  5. 1.054 = (1 + r)^1
  6. r = 5.4%

Part b) Calculating the Value of the Loan After 10 Years

We can use the compound interest formula again to determine the value of the loan after 10 years:
A = £7,500(1 + 0.054)^{10}

After calculating, the amount would be ~£12,974.64.

Therefore, the future value of the loan after 10 years, rounded to the nearest 1p, is £12,974.64.

User Sandro Paganotti
by
8.4k points