Maths Guru???

30dirtybirds

Hi All,

Anyone a bit clever with arithmetic?

See the attached scan, from that can any body tell me what amount is from cash and what amount is from purchases? is it possible to reverse calculate?

If so I'd love it if you could also show your workings, so I could learn a little too

Thanks in advance
Jamie

Stinkybell

How many days have there been since your last statement? Check the dates of both as that will give you how many days you've been charged interest for and we can maybe work out a ratio

30dirtybirds

Hi Stinkybell,

Unfortunately I don't have a previous statement, I've been binning them somewhat in denial I think.

But that's the June statement (only one I could find) and so I presume 31 days since the May one...

NickX

We can only make an estimate because we don't know precisely when the transactions were made, however I think the Cash Balance is around £1100, and the rest is Purchases.

Stinkybell

Not sure if this is exactly right, but will give you an idea. Assuming that there have been 28 days since your last statement, then your monthly rate of interest will be as follows:
Cash: 0.073% x 28 = 2.117% monthly interest (£22.96)
Purchases: 0.064% x 28 = 1.856% monthly interest. (£134.31)

Using ratios, we can then infer that if 2.117% of a number is £22.96, then 100% of the number (and the total Cash owed) would be £22.96 / 0.02117 = £1084.55
and for cash £134.31 / 0.01856 = £7236.53

This then gives you the approximate value of
Cash = £1084.55
Purchases = £7236.53
Total = £8321.08

As NickX rightly pointed out, there will be some transactions that mess it up a bit, and it also depends on when in the month you made your payment, but it gives you a good idea of the values

NickX

That is pretty much what I did aswell.

I then pro-rated the figures against the statement balance of £8358.50

i.e. Cash Balance of £1011.90 pro-rated :

1011.90 * (8358.50 / 7781.56) = £1086.92

Hence my estimate of about £1100 cash balance.