If I have one 10p piece and one £1 piece. The average total is 55p.
If I have a thousand 10p pieces and one £1 piece, it isn't. It's just about 10.1.
This might be of interest to non-mathematicians like myself and Jarrah White.
Maths was my worst subject at school, but checking in my head only, I instantly agreed with Mag40's first average of 55p.
1.1 ÷ 2 = .55
But I had to get out the calculator for the second line, and got a very different answer. My 0.1008991 versus "just about 10.1."
So I wondered if 10.1. indicated a ratio or something else I was ignorant of, so I next had to check how many new p in a new £, because when New Zealand converted to decimal currency on 10 July 1967, £1NZ became NZ$2 and 10 shillings became $1. I remember it well because I took my girlfriend to lunch that day and we were both amused at the new "play money" we had. Many of the $ c. coins and notes were smaller than £ s. d. coins and notes.
Mag40's first line tells me there's 100 p in a new £, so I could do the sum as if I'm using New Zealand currency. So why the difference?
The buttons I pressed on the calculator were:
1000 x .1 + 1 ÷ 1001 =
and it answered: 0.1008991
Now, apparently there's the way el-cheapo calculators work and there's also that BEDMAS stuff and proper algebraic notation (IIRC) to consider, and if I put the above sum into my spreadsheet and my scientific calculator, they both give an answer of 100.000999. So that produces another complication -- now there are three very different answers.
Breaking down my sum, it becomes:
1000 x .1 = 100 (1000 10p coins = £100)
100 + 1 = 101 (£100 + £1 = £101)
101 ÷ 1001 = 0.1008991 (£101 ÷ 1001 coins = £0.1008991)
If you're reading this, Jarrah, what answer(s) do you get?
10.1 or
0.1008991 or
100.000999 or
something else?
Real mathematicians will probably be laughing at what I missed, but I think I've figured it out now, and that Mag40 should have put a
p in the second line. But maybe that's not how such sums are written in the UK.
By the way, I can still add small columns of £ s. d. (pounds, shillings and pence) in my head, but my late father would be horrified at how slow and how inaccurate I occasionally am.
On the other side of the coin, last weekend I bought a $3.30 ice cream at my local shop, and a kid of about age 12 to 14 was serving, so I said I'd only pay him if he could tell me how much change he had to give me from $4. He had no idea and had to ask the owner, whose eyebrows shot up! Teenagers in NZ nowadays can't do sums that I could do when I was about 7 or 8 -- they instead rely on electronic devices and batteries never going flat and electricity never being cut off, which often happens where I live, rurally.
Our very last power disruption was a weird, unusual one where the current or wattage somehow diminished but stayed running. Lights dimmed considerably, but refrigerators and TV sets wouldn't function. I switched everything off in case appliances got damaged and lit a candle. Eventually the power was cut off for about 30 minutes when repairmen must have found the fault, then it was switched back on and was normal. But I wonder what caused that fault, which I've never experienced before. It was a windy night with light showers, so maybe a wet tree branch touch power lines and drained some of the current.
