Brian invests £4000 into his bank account. He receives 7% per year compound interest. How many years will it take for Brian to have more than £8000?

11 years give or take

FV ==PV x [1 + R]^N

8000 ==4000 x [1 + 0.07]^N, solve for N

8000 ==4000 x 1.07^N

8000/4000 ==1.07^N

2 == 1.07^N

N ==Log(2) / log(1.07)

N ==10.245 - years to double your 4000 to 8000 pounds.

To get MORE than 8000 pounds, you will need about 10 years and ~4 months.