What's my average account balance?

[ferrariF50lover]

Hi guys,

I was going to ask in the Finance sub-forum, but my word, what a fking terrible species of self-congratulatory aholes.

Imagine I have a bank account. In month 1, I deposit £1200, and for the next 11 months I deposit £200/month. Come the end of month 12, the account is worth £3400.

My maths keeps telling me that the average balance was £1700, but what with the 'uneven' spread of the credit payments, that just doesn't feel quite right.

I don't need to know for any reason, the question occurred to me while I was playing with the dog this evening. It's not often a maths question has me stumped, but this one does.

Any ideas?

[size]

Your skint.

[anonymous-user]

Work it out on a daily basis.

Do a spreadsheet. Rows 1-31 enter 1200. Rows 32-59 enter 1400. And so on up to 365.

Sum the total and divided by 365. That's your average. ETA: which is £2,305.21.

Edited by anonymous-user on Friday 2nd September 23:37

[brrapp]

Greg66 said:

Work it out on a daily basis.

Do a spreadsheet. Rows 1-31 enter 1200. Rows 32-59 enter 1400. And so on up to 365.

Sum the total and divided by 365. That's your average. ETA: which is £2,305.21.

Edited by Greg66 on Friday 2nd September 23:37

Almost got the same answer by a lot quicker method.
half of (final sum minus starting sum ) added to starting sum=2300
i know this is working out the median rather than the mean balance, but as the monthly pay-in was evenly spread throughout the year, it should give the same figure.

[SpamDisco]

(1200+1400+1600+...)/12=2300

[FN2TypeR]

size said:

Your skint.

Your* wrong.

• sic

[Some Gump]

ahaha, some self congratulatory tt moved it to finance.

It was not even a finance question, it was maths.

Brilliant.

[anonymous-user]

brrapp said:

Almost got the same answer by a lot quicker method.
half of (final sum minus starting sum ) added to starting sum=2300
i know this is working out the median rather than the mean balance, but as the monthly pay-in was evenly spread throughout the year, it should give the same figure.

The payments in are not quite evenly spread because the months are different lengths. And a longer month at the end of the year when the balance is high pulls the average up compared to a short month early in the year when the balance is low.

[ferrariF50lover]

Thanks all, especially to whichever mod moved the thread. I wonder if I'd asked about putting beans into a tin whether it would have been moved to the food section?