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On 18/01/13 18:04, Tom Davies wrote:
Hi :)
That was my approach too but then i forgot to send my spreadsheet to Hylton and by the time i 
remembered Jay had produced an answer that took it to the next level.  I think it's good to see 
these sorts of problems occasionally because it pushes us outside of our normal thought processes.
Regards from
Tom :)

I still await that spreadsheet Tom :)

I hope the further explanation I sent the list makes it thru this time.

Please forward it to me via pvt email.



From: Dan Lewis <>
Sent: Friday, 18 January 2013, 15:34
Subject: Re: [libreoffice-users] Calc sliding scale formulae?

       Perhaps the private suggestion was correct. Perhaps your understanding of Algebra is not as 
good as it needs to be. After all this is an Algebra problem.
       Now for some questions:
1. How much will 1 to 150 units cost? What is the formula to determine this?
2. How much will 151 to 599 units cost you? What is the formula for this?
3. How much will 600 units cost? What is the formula to determine this?
4. How much will 601 or more units cost you? What is the formula for this?
5. What is the cost per unit for any given number of units? What is the formula for this? (Hint: 
this is a very simple division problem.)
Hint: I have asked you for 5 formula, and that is also the number of cells you will need: one cell 
per formula. You will be using a result in some cells in the formula in another cell.


On 01/18/2013 07:00 AM, Hylton Conacher (ZR1HPC) wrote:
It has been privately suggested to me that I want my work done for me, however, whilst I have had 
theory from the list on how the formulae should work, I have not had anyone indicating how I can 
get Calc to only use a particular formula range until its result exceeds the amount allowed for 
that formula, and to then use a different range for the remaining value.

My email below indicates the scales used, and please see below for the calculation of the number of 
units per pricing bracket obtained, using a calculator.

What is the main problem is getting Calc to only use a formula up until a max value before moving 
onto the next formula.

Assuming I purchased R2000 of the unit(electricity). As per the scale I would get 150 units at 
R1.29 which would equate to R193.50, which leaves a further R1806.50 that was used to buy 
electricity, but at different rate per unit.

Taking the remaining R value and dividing it by 1.35(being the next value in the sliding scale) 
provides an answer of 1338.1 units. Only 450 units are allowed to be purchased at this price 
however, so 450*1.35=R607.50.

So all in all we have only spent 193.50 and 607.50 = R801.00 out of R2000.

Therefore the remaining R1199.00 divided by 1.60(being the next value in the sliding scale) = 
749.38 units.

Therefore our R2000 purchased 150+450+749.38=1349.38 units.

I trust the above better explains what I need Calc to do. Perhaps it is not possible, but I 
challenge you all to solve this one.

On 01/10/2013 10:38 AM, Hylton Conacher (ZR1HPC) wrote:

I am using Calc 3.4.5 on openSuSe Linux 11.2

I am working on a spreadsheet to cater for the monthly measurement of
household electricity consumption, new unit purchase and costing of
used units.

The electricity supplier gives me the first 150 units of electricity
at R1.29 per unit. The next 450 units are costed at R1.35 per unit.
Thereafter the units cost me R1.60 per unit. The monetary values per
set amount of unit changes when the electricity provider increases
prices i.e. the first 150 units might increase to R1.50 per purchased
unit, the next 450 units might be costed at R1.55 and thereafter units
will cost R2.00.

Each time I purchase electricity the units I am allocated are based on
the above sliding scale starting from 0.

How can I work out the number of units I will receive for a given
currency value i.e. R2000.00? i.e. x @ R1.29, y @ R1.35 and z @ R1.60=

In addition how could I work out the value of units consumed using the
above scale?

I am assuming the R values in the scale will change over time and
these can each be averaged to calculate the cost of units used, but
the problem is still to work out the formula.

Anybody have an idea if this is possible and where to start?

I am investigating results found on Google but would appreciate a
pointer or three.

If I understand your problem, you have a general equation of ax + by +
cz = d where a = 150, b = 350, c is currently unknown, d = 2000 (or any
value you choose), x = 1.29, y = 1.35, and c = 1.60. Solving for c, you
get c = (d - ax - by)/z.

Average cost per unit, ave, is ave = (a + b + c)/d., if I understand
your question The value c must be calculated prior to this step. In
terms of a Calc formula the c value would reference the cell with the
previous calculation.

In your spreadsheet I would set a table with named cells for each value
(a1 is Base_Rate and is 1.29, etc) so you can easily change the values
and see the values used.

Hylton is a Lions Club member of Lions Club of Fish Hoek (District 410A) being part of the worlds
largest non profit NGO

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