Looking for a mathematical formula

[tech291083]

Hi,

Lately I have been doing some numeracy tests in order to prepare myself for a test based interview as it seems to be the case with some of the firms hiring these days. Here is the question. I can not get my head around it. In fact I can get the answer doing it manually, but I think there a mathematical formula available to work this kind of problems out. Thanks a lot.

A town with a population of 2000 grows at a rate of 30% per annum. What will be its population in the next 4 years?

[pam]

How about 2000 * (1.3 ^ 4) ?

or to state as a formula where p is initial population, g is annual % growth and y is number of years:

p * (((100 + g) / 100) ^ y)

However, I am probably over simplifying here as population will be growing continually throughout the year and at any point in the year, growth will be 30 % of that population per annum (hmm need "my ears are bleeding smiley) . If we turn it in to say, an interest on savings question where interest is calculated once a year, then I think the formula is valid.

[mechdave]

This problem looks alot like what I did in grade 10 maths class, at the time I was calculating compound interest! The formula I came up with is on the compund interest wiki it is as follows:

FV = PV ( 1+i )^n

where Fv is Future value (final population), Pv is initial population, i is the interest rate (or population rate) as x/100 (ie. 30/100 = .3) and n is the number of years

Incedently it is exactly the same as what Pam has said

[tech291083]

Thanks guys, ya it is very much like calculating the compound interest....