Well, ummm, well. I find it a bit amazing the 35.3 oz, 36 oz, 37 oz, and 37.57 oz are all exactly 1 kg. They in fact aren't. The product that claims 35.3 oz is probably really 1 kg (actually to make that claim, it must be >1.0007 kg, but they have to round down to three sig. figures). The others, as the larger claim must be true (on average) must be at least 1.02 kg, 1.0489 kg, and 1.065 kg respectively. The last two are sufficiently in error that if the metric claim were used for the unit price, it would be noticably over-stated. It is legal for them to understate the metric claim, but obviously, they are not very serious about its accuracy. I do not believe metric is the basis of fill, except perhaps for the product which also claims 35.3 oz. The 37.57 oz / 1.0 kg claim is most odd, given the precision of the Customary claim; I wonder if someone made a math mistake --- On Sun, 2/12/12, Carleton MacDonald <[email protected]> wrote:
From: Carleton MacDonald <[email protected]> Subject: [USMA:51462] Re: Calculating prices with grams and ounces To: "U.S. Metric Association" <[email protected]> Date: Sunday, February 12, 2012, 6:25 PM Purchased recently at Costco, these four items, all at a VERY rational size. Admittedly these are larger than what you get at regular grocery stores but it is interesting that an even metric size was chosen for all. Carleton From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Sunday, February 12, 2012 05:55 To: U.S. Metric Association Subject: [USMA:51459] Re: Calculating prices with grams and ounces The problem is that the manufacturers in the US are not ‘thinking metric’. If the cereal package was a logical metric size (say 500 g), then the issue starts to look much easier. The unit price then would (most likely) be in $/kg – in your example $7.72/kg. And that actually is an interesting price point. Here in the UK, where unit pricing is usually in £/kg (occasionally £/100 g, but easy to move the decimal point one place to convert to £/kg), £7/kg (or £0.70/100 g) is a common pricing level. Cheese, fresh fish, many meats etc. often come in somewhere in the region of £7/kg. I find it a very useful comparator in assessing whether something is good value or not (obviously depends on the product – imported gourmet cheese is often priced at around the £10 to £12/kg level). So a package weighing, say, 250 g, and costing say £1.48, can be easily worked out at 4 x 1.48 – say 4 x 1.50 for ease of calculation = £6/kg. That is under my £7/kg pricing comparator level, so probably a good buy (again, depending on the product). Multiplying is always easier than dividing, and for anything weighing less than 1 kg, you can usually use multiplication rather than division to work out its unit price per kg. Having to use oddball sizes like 368 g (compared to 13 ounces) is always difficult. If say the weight was 375 g (still a bit of an oddball size, but at least exactly halfway between 250 g and 500 g), that would then be an odd size in ounces, which surely makes calculating non-metric unit prices (where not given) much more difficult. John F-L From: Paul Rittman Sent: Sunday, February 12, 2012 5:22 AM To: U.S. Metric Association Subject: [USMA:51457] Calculating prices with grams and ounces The last few times I went shopping for breakfast cereal, I tried to compare the prices of various cereals on a per-ounce or –gram basis. Tonight, one cereal I bought was $2.84, and the package said it weighed 13 ounces or 368 grams. Calculating the price per ounce seems to be much easier than calculating the per gram price. I was able to quickly see that it costs about 20 cents an ounce (quite a bit cheaper than most other cereals) by multiplying 13 x 2, and then adding a zero. I then decided to try to get the cost per gram, but decided not to even try to put 368 into 284. After a similar experience shopping last week, I saw that 20 cents an ounce was roughly equal to 0.7 cents a gram. I’m not sure that I want to multiply the number of grams by 7, and then move the decimal. Another option I thought of was to take a tenth of the gram total, and then subtract it 3 times (from that total), to see if the price was at 0.7 cents a gram or lower. Still, it seemed like a lot more work. I know folks can say it’s just that I’ve just gotten used to imperial measurements, but it does seem a lot easier to me to use when shopping, that’s for sure. Now I know that if our country were officially metric only, the supermarkets would be posting the prices in metric terms on the labels on the shelves, but honestly I don’t like to use them because the writing is so small (even when they are given with imperial units). OK now—is this simply a math process that I’ve forgotten about, that will allow me to calculate as easily with grams? Or is this simply an area where working with imperial units is easier? I am well aware of the various advantages of the metric system…. is this just an example of no system being perfect? No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.1913 / Virus Database: 2112/4803 - Release Date: 02/11/12
