4 ms·

I'm a big fan of estimation: If you've ever seen the guys refilling the machine, you know it's got a slot for every drink button. There are about eight button

by donw 16y ago

I'm a big fan of estimation: If you've ever seen the guys refilling the machine, you know it's got a slot for every drink button. There are about eight buttons on the average machine, and I'm guessing that each row holds about a case of soda -- 24 units (cans or bottles). So, that's 192 refreshing beverages per machine. Now, they don't just wait until everything is empty to refill, and not every customer is going to pay with two $1 bills. So, let's make a couple of assumptions: 1. They refill the machine when it's about half-empty, so you only need change for about half of what the machine holds. 2. If you put in $2, you get back $0.75 in change (if the soda is $1.25), but we don't need to do that every time. 3. Given the usage patterns that I've observed, I'm figuring that we only need to provide change for about every third bottle, so we need about a quarter for every drink unit that we sell. Put those together, and you get $24 in change.

pmccool 16y ago
This assumes that the change dispenser is emptied at the same time that the machine is refilled. This is a reasonable assumption, but not a self-evidently correct one.
- VengefulCynic 16y ago
  I know in the grocery store (in the US) where I worked in high school, this was incorrect. The store was responsible for sticking the change, the armored truck was responsible for collecting the receipts, and the vendor was responsible for stocking the product. Granted, this is the most complex case and relies on the abnormal relationship that vendors have with supermarkets, but I would suspect that it represents a nontrivial percentage of machines.
jgrahamc 16y ago
I love that. I had to do a similar calculation for how much change would be needed for a film festival. I was a volunteer that handled the cash and we needed to know how many $1, $5, $10 and $20 bills to have on hand so that we could always accept cash when people bought tickets. I did a similar calculation making reasonable assumptions (most people buy two tickets at a time, most people pay with a $20 bill, etc.). It was fun and worked out quite accurately. Best part was taking the actual funds collected and reevaluating to minimize the amount of cash needed.

by donw 16y ago

pmccool 16y ago

This assumes that the change dispenser is emptied at the same time that the machine is refilled. This is a reasonable assumption, but not a self-evidently correct one.

VengefulCynic 16y ago
I know in the grocery store (in the US) where I worked in high school, this was incorrect. The store was responsible for sticking the change, the armored truck was responsible for collecting the receipts, and the vendor was responsible for stocking the product. Granted, this is the most complex case and relies on the abnormal relationship that vendors have with supermarkets, but I would suspect that it represents a nontrivial percentage of machines.

jgrahamc 16y ago

I love that. I had to do a similar calculation for how much change would be needed for a film festival. I was a volunteer that handled the cash and we needed to know how many $1, $5, $10 and $20 bills to have on hand so that we could always accept cash when people bought tickets. I did a similar calculation making reasonable assumptions (most people buy two tickets at a time, most people pay with a $20 bill, etc.). It was fun and worked out quite accurately. Best part was taking the actual funds collected and reevaluating to minimize the amount of cash needed.