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?

[Infarction]

With a growth rate of 30%, it'll be at 130% after each year. Since that compounds, you'll just have a simple formula of:
[tex]pop = 2000(1.3^x)[/tex]
This assumes the compounding happens at one instant per year, rather than calculating continuously.

Plug that in, and you'll get 5712

[WaltP]

pop = 2000
Loop 4 times
    pop = pop + (pop * 30%)
end loop

[tech291083]

Thanks a lot guys makes sense to me. But here I have got another question and the book has given its answer as 2 to the power of 5 meaning 32. Here is the question.

A culture of bacteria grows by a ratio of 1:2 every two hours. What will be the siez of the culture after 10 hours.

Sorry to bother you again, but this is something that has been bothering me day and night for quite some time now. Thanks....

[tech291083]

Thanks a lot guys makes sense to me. But here I have got another question and the book has given its answer as 2 to the power of 5 meaning 32. Here is the question. A culture of bacteria grows by a ratio of 1:2 every two hours. What will be the siez of the culture after 10 hours. Sorry to bother you again, but this is something that has been bothering me day and night for quite some time now. Thanks....

Here is another one:

A currency loses its value by a factor of 0.02 a year. What % of its original value will be remaining after 5 years. Express you answer to the nearest full percentage.

Thanks...

[WaltP]

These are all the same basic equation.
Calculate the first value from the original value.
Use that new value and calculate again.
Repeat the specified number of times.

[joshSCH]

These are all the same basic equation. Calculate the first value from the original value. Use that new value and calculate again. Repeat the specified number of times.

lol yea.. they seem like homework problems to me...

[MidiMagic]

Kirk: "There must be thousands of them, tens of thousands..."
Spock: "One million, seven hundred seventy one thousand, five hundred and sixty one. That's assuming they got in here six days ago, and a litter of ten each day."

It's the same formula, in this case 11 ^ 6.