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Ryan, Engineer
Category: Calculus and Above
Satisfied Customers: 9218
Experience:  B.S. in Civil Engineering
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Need help with an exponential formula. Given the following

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Need help with an exponential formula. Given the following statement with the min and max values...min:{
A: 200,
B: 2400
A: 2500
B: 75
}How do I calculated the value of B, with a specifc value of A ( between 200 and 2500 ). So to summarise with an example, if B = 1459, what formula can I use to get the value of A?


Thank you for using the site. I'll be happy to help you with this problem.

I'll have a solution posted for you shortly.



Hi again,

Here is a link to the solution:


Please feel free to ask if you have any questions about this solution, and please let me know if you have any trouble accessing the file at that link.



Customer: replied 4 years ago.
Thank you that looks great, will look in detail at it tomorrow and I'm sure mark it as solved.

You're quite welcome.

Customer: replied 4 years ago.
Hi, ok thank you for the very clear answer. What if I had a value for A and wanted to find B? Or do I need to post this as another question?
Customer: replied 4 years ago.
Sorry, it's late...correct me if I'm wrong but I think you already answered that in your calculations...(incorrect format but ) B=3239.66e -0.0015A

Then you would use the first formula:

B = 3239.66 * e^(-0.0015 * A)

So, if you had A = 531.81, you would get:

B = (3239.66)*e^(-0.0015 * 531.81)

B = (3239.66)*e^(-0.7977)

B = (3239.66)(0.4504)

B = 1459

Either formula will work both ways. It's just that if you have A and want B, you would use the above formula. And if you have B and want A, you would use the second one.

No need to apologize, by the way. I'm happy to help.

Customer: replied 4 years ago.
Ok, one more question, after which I'll be rating your response excellent.
I need the formula for some code so I need to convert B = 3239.66 * e^(-0.0015 * A) into Javascript. My Maths is very poor, am I correct the 'e^' is the symbol for exponential ( can I use 2.71828? ). So in non-mathematical longhand it's...
B= 3239.66 * ( 2.71828 * ( -0.0015 * A ) )

Not exactly, since the (-0.0015 * A) part is an exponent, and not a factor.

You can do something like this in Javascript:

B = 3239.66 * math.exp(-0.0015 * A)

Alternatively (but equivalently), you could use:

B = 3239.66 * math.pow(2.71828, -0.0015 * A)

Ryan and other Calculus and Above Specialists are ready to help you
Customer: replied 4 years ago.
Many thanks.

You're very welcome. I'm glad that I could help.

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