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Thread ID: 96566 2009-01-15 02:15:00 Math doing my head in -- Is this even possible? How good at math are you? Chilling_Silence (9) PC World Chat
Post ID Timestamp Content User
738793 2009-01-15 02:15:00 OK,

So I thought I'd try and be a clever bugger and put this in to a spreadsheet.

If I know:
The total number of minutes somebody spent making calls to a type of destination
The total number of unique calls made
The total cost of it all

Can I work out the base per-minute cost from this?

Im trying to go over this in my head for 2 examples:
Example1:
(a) Number of Local Calls 500
(b) Local Calls total time (Mins) 291
(c) Cost $25.05

Example2:
(x) Number of National Calls 500
(y) National Calls total time (Mins) 768
(z) Cost $153.6

Now, I know because I put this together that the answer to Example1 is .05
The answer to Example2 is .2
However Im not entirely sure how i can use the same formula and get the same example every time.

In Example1, they made 499 calls that were <1 minute, and 1 call that was exactly 2 minutes long (Hence that call cost them 10c rather than 5c).

Im just not sure of the math to work this all out, as all calls must be charge for at least 60 seconds worth, and then per-second after that.
So a 60 second Nation call is 20c
A 90 second local call is 30c

Is this even possible to work out? Ive spent the last hour or two going over this but I just cant quite get my head around it ;)


Chill.
Chilling_Silence (9)
738794 2009-01-15 02:58:00 Wouldn't you need to know the duration of each unique call? the_bogan (9949)
738795 2009-01-15 03:26:00 Potentially .. however you know the number of calls, so you know that if there's 500 national calls, then they're going to be billed at least $100
Anything on-top of that is because a call has exceeded 1 min.

Im not entirely sure if its actually possible, hence why I thought I'd ask ;)
Chilling_Silence (9)
738796 2009-01-15 03:51:00 So assuming there is a flag fall minimum charge then the total charge will be
(Total unique calls x minimum charge) + ( (Total duration of all calls - Total unique calls) x per minute rate)

- minus "Total unique calls" because they have already been charged for in the first part

??
Ofthesea (14129)
738797 2009-01-15 04:03:00 If every call gets charged for at least one minute it seems like you're missing a piece of information there.

The problem is you have no way of knowing how much 'free' time you've lost due to the 1st minute rule.

Your first example could be solved many ways:
With 500 calls each 35 seconds long.
- This would result in a 'high' per minute charge.
With 499 calls each 1 second long and a very long phone call making up the remaining minutes.
- This would result in a 'low' per minute charge
Something in between.
- This would result in a charge between the high and low rates.

Disclaimer: Thought about after a long day thinking about other numbers :)
shermo (12739)
738798 2009-01-15 04:50:00 i'm such an idot
number of minutes divided by price?
pcuser7895 (12979)
738799 2009-01-15 05:30:00 So its logically not possible then ? Chilling_Silence (9)
738800 2009-01-15 09:54:00 Wait wait.

If you only want the per-minute cost then surely all the calculation needs is this:

Total Cost/Total Number of Minutes
beeswax34 (63)
738801 2009-01-15 11:48:00 Not *quite* that easy.
If every call was charge in 1-min increments then sure, however its only the first minute thats charged as a "whole" minute.
If you use that on Example1:
(a) Number of Local Calls 500
(b) Local Calls total time (Mins) 291
(c) Cost $25.05
25.05 divided by 291 you get 8.6c which is wrong ... :(


Shermo, the times above are in Minutes, not seconds ;)
Chilling_Silence (9)
738802 2009-01-15 13:05:00 What is the right answer btw? beeswax34 (63)
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