Question

Alex invests £4000 for 7 years.
His investment pays compound interest of x% per annum.
At the end of the 7 years Alex’s investment is worth £5263.73
Work out the value of x

Answer 1

Answer:  x=4% i.e.

Rate of interest = 4% per annum.

Step-by-step explanation:

Since we have given that

Amount Alex invested = £4000

Number of years = 7

Rate of interest = x%

Amount she received at the end of 7 years = £5263.73

We will use " Compound Interest " formula :

$A=P(1+\frac{r}{100})^n\\\\5263.73=4000(1+\frac{x}{100})^7\\\\\frac{5263.73}{4000}=(1+\frac{r}{100})^7\\\\\frac{526373}{400000}=(1+\frac{r}{100})^7\\\\1.3159325=(1+\frac{r}{100})^7\\\\(1.3159325)^{\frac{1}{7}}=1+\frac{r}{100}\\\\1.04=1+\frac{r}{100}\\\\1.04-1=\frac{r}{100}\\\\0.04=\frac{r}{100}\\\\4=r$

Hence, x=4% i.e.

Rate of interest = 4% per annum.

Answer 2

Answer:

x=4%

that will get you all the marks lol