Probability & Profit

[Guest]

I'm having a problem creating a formula to calculate % profit, despite being
able to calculate it mentally!
A product costs £10, and either has to sell for £100, or be thrown away.
The probability of it selling is 1 in 5 (or 20%). Therefore if I make 10 at
a cost of £100, I will sell 2 @ £100 each taking £200, or 100% profit on my
outlay.
What formula and/or function will calculate this for me ?
Any advice much appreciated ?

 

[Bob Phillips]

=(num_made*probability*sale_price)/(num_made*cost_price)

or

=(sale_price/cost_price)*probability

--
HTH

Bob

(there's no email, no snail mail, but somewhere should be gmail in my addy)

 

[Guest]

Many thanks for your help, though I dont think we're quite there yet? The
solution to my example should be 100%, but your suggestion is returning 200 ?
Perhaps I'm not entering the probablity in the correct fromat i.e. 20, 20%,
20/100 ?
Regards
Graham

 

[David Biddulph]

Bob forgot to subtract the cost from the sale proceeds to evaluate the
profit.
Try =(num_made*probability*sale_price -
num_made*cost_price)/(num_made*cost_price)

 

[Guest]

Thank you both for your help, what I eventually got working was:
=SUM(((Profit*probability)-Cost)/Cost)*100