Exponential growth

[Lestrygonians]

Hope you can help with this. I am trying to use the formula f(x)= a(1+r)¹² for the following situation but I think I must be using the formula incorrectly. I have a small investment that is growing by 50% per month. What will it be after 12 months? Is this the same as the compound interest formula?

 

[Deleted member 4993]

Hope you can help with this. I am trying to use the formula f(x)= a(1+r)¹² for the following situation but I think I must be using the formula incorrectly. I have a small investment that is growing by 50% per month. What will it be after 12 months? Is this the same as the compound interest formula?

Please show us:

How you are using the formula (with numbers)? ...... and...

Why do you think you are using the formula incorrectly?

 

[Lestrygonians]

Please show us:

How you are using the formula (with numbers)? ...... and...

Why do you think you are using the formula incorrectly?

20(1+r)¹²
20(1.5)¹²
30¹²
on my calculator 30 key x^y= some 18 digit figure that can't be right
Where am I going wrong?

 

[Deleted member 4993]

20(1+r)¹²
20(1.5)¹²
30¹²
on my calculator 30 key x^y= some 18 digit figure that can't be right
Where am I going wrong?

First of all - you need to evaluate the E(xponent) of PEMDAS before M(ultiplication)

so you should calculate (1.5)¹² first - then M(ultiply) by 30.

Remember PEMDAS......... (or PEDMAS or BODMAS... whatever way you were taught)

Now what do you get.....

 

[Steven G]

Before you multiply you need to know what you are multiplying! You are multiplying 20 and 1.5^12. There is no multiplying 20 and 1.5 in this problem.

 

[Steven G]

First of all - you need to evaluate the E(xponent) of PEMDAS before M(ultiplication)

so you should calculate (1.5)¹² first - then M(ultiply) by 30.

Remember PEMDAS......... (or PEDMAS or BODMAS... whatever way you were taught)

Now what do you get.....

This is exactly what I am talking about in my other post!

 

[Deleted member 4993]

This is exactly what I am talking about in my other post!

No ... here PEMDAS was NOT applied (may be it was taught without much emphasis - by somebody like....)

Apply PEMDAS ... and you are golden.

 

[Steven G]

No ... here PEMDAS was NOT applied (may it was taught without much emphasis - by somebody like....)

Apply PEMDAS ... and you are golden.

Knowing what you are multiplying is a simple concept to remember. It is crystal clear to all students that before you multiply you need to know what you are multiplying.

 

[Lestrygonians]

20(1+r)¹²
20(1.5)¹²
30¹²
on my calculator 30 key x^y= some 18 digit figure that can't be right
Where am I going wrong?

well if I was taught pedmas or bodmas I have forgotten. It was 40 years ago and I have never used it since like all the other maths I learned in school. So if my initial amount is 20 then I should work out the (1+r)¹² first and then multiply it by 20

so then (1+r)¹²= (1.5)¹² = 129.75 (rounded)times that then by 20 = 2595 (rounded)
is this correct then that 20 becomes 2595 in a year?

 

[lookagain]

so then (1+r)¹²= (1.5)¹² = 129.75 (rounded)times that then by 20 = 2595 (rounded)
is this correct then that 20 becomes 2595 in a year?

Don't round (to two decimal places) after you raise 1.5 to the 12th. Keep as many
decimal digits in the display as you have, multiply that by 20, and then round once
at the end. Does the problem require the answer to the nearest whole number of
dollars or nearest cent?

 

[Lestrygonians]

I require the answer to the nearest euro and cents. I am not a scholar doing maths for homework so it is immaterial to me. I just needed to know if the claim that my investment would grow 100 fold in a year was correct and it seems so. Thanks for the help. There is a second half to this question if you will indulge me. If I wanted to take a fixed amount (not a percentage) out of the monthly return, how do I build that into the formula/function? For instance if my €2500 investment in yr 2 were to grow at the same 50% per month and I wanted to take out €500 per month how would this affect the formula?

 

[Lestrygonians]

Anyone??

 

[Deleted member 4993]

I require the answer to the nearest euro and cents. I am not a scholar doing maths for homework so it is immaterial to me. I just needed to know if the claim that my investment would grow 100 fold in a year was correct and it seems so. Thanks for the help. There is a second half to this question if you will indulge me. If I wanted to take a fixed amount (not a percentage) out of the monthly return, how do I build that into the formula/function? For instance if my €2500 investment in yr 2 were to grow at the same 50% per month and I wanted to take out €500 per month how would this affect the formula?

Post your second problem in a separate thread - so that it gets proper attention.