An e-mail from an old pal

A few weeks ago, I received an e-mail from someone I hadn't seen for 35 years or so. We exchanged details of our lives in the intervening period, he was a director of a scrap metal company and when he saw that I was selling watches, he included this little snippet of information in his last e-mail:

Quote:

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Of interest to you, 2yrs ago we bought 1500kgs of scrap watches.Makes included Rotary,Citizen,Calvin Klein and even Maurice Lacroix etc.Lots of them were perfect or just needed a new battery.Good pickings for everyone.

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Gutted!

Eddie

Strewth!!!
:shock: :shock: :shock:
Mike

I'm sorry to hear that, Eddie. A treasure trove lost to heathens, no doubt.

I recently got 15 movements (had to buy them, but they were cheap). A couple of 1 jewel movments in there, which I've never seen before. But also one I really wanted (a spare, working, FF 96). There were also about 4 others that look interesting. Including this little gem, a FF 55, which started up when I accidently turned the stem a couple of clicks.

http://kant1.chch.ox.ac.uk/watches/temp/ff55.jpg

Best wishes,
Bob

PS Any excuse for a picture. :)

1500kg!? :shock:

Jeez! Bob, I keep meaning to get in touch with you when I'm in Oxford - was up there today but running about like mad trying to meet everybody. Soon!

Ming

Feck.

By the law of averages, there was probably a hundredweight of Rolexes and at least a pound of Pateks in there too...

OK. Your starter for 10.

Assuming that all the watches were steel, that 20% were on metal bracelets, that each bracelet weighed double its leather strap equivalent, which weighed between 8 and 10 grammes, approximately how many watches did it take to make up the 1500kgs?

Please show each step of your calculation.

Don't think it can be done without making an assumption on the weight of the watch head.

If the average weight of the strap is 9g then the average weight of a bracelet is 18g. As there are 20% bracelets then:
Average weight of the fastening = 0.2[18] + 0.8[9] = 10.8g

Since the total weight of the watch [W] is the weight of the head [Wh] plus the weight of the fastening then:
W = Wh + 10.8

If the total number of watches is N then
W x N = 1500kgs

Substituting and using consistent units
[Wh + 10.8] x N= 1500000
N = 1500000 / [Wh+10.8]

If we assume that the weight of a steel watch head is 125g then
N = 1500000 / [125 + 10.8]
N = 11046 to the nearest whole number

Cheers, Olly

Edited to use square brackets instead of rounds as the round brackets end up as short code for the emoticons!

I think probably more, if they're complete watches - say an average of 100g each, to give 15k watches. Don't think they'd have that much weight, seeing as they're probably older watches.

Of course, if it was movements only, then at an average of 20g per movement, that's 75,000 movements...:shock:

Ming