[fizzbuzz]

Ok, so revising again for tomorrow
and i have done the first two parts of this question, but have no idea about the third. please help

Ever £1 of money invested in a savings scheme continuously gains interest at a rate of 4% per year. Hence after years, the total value of an initial £1 investment is, where

(a) sketch the graph [done, and not relevant]

(b)Calculate, to the nearest £, the total value of an initial £800 investment after 10 years. [done, got £1184, correct]

(c)Use logarithms to find the number of years it takes to double the total value of any initial investment. [whhaat!?]

so i did this,








but i have two unknowns, please help

[cheemaj187]

you are being asked to find x, the number of years it takes for the initial investment to double. Y is the final value of the investment, so if you were to invest £1 initially you need to find x when y is equal to 2.

what is the answer by the way? just so i can be sure i havent done it wrong as well :P
the number of years it takes for any initial investment to double is true.

your initial value will be be at x=0

so

hence for the initial value y=1

when the initial investment doubles it will be equal to 2y

hence:



we know that for an initial investment of £1 y=1

so

[fizzbuzz]

answer is 17.7, (3sf) ok ill have a go with that, thanks

[maths-enthusiast]

Take logarithms. Done.

[cheemaj187]

Originally Posted by fizzbuzz

answer is 17.7, (3sf) ok ill have a go with that, thanks

yep my method works, see my post above

[fizzbuzz]

thank you both, i got it