I have just done an S1 past paper and am marking it (edexcel, june 02, if anyone cares).
One of the questions says
The labelling on bags of garden compost indicates that the bags weigh 20kg. The weights of a random sample of 50 bags are summarised in the table below.
Blah blah, table.
b) Using the coding blah blah, find an estimate for the mean and standard deviation of the weight of a bag of compost.
So I think "Aha! It says it's a SAMPLE, so I must use the s.d. for a SAMPLE formula, i.e. the one with 1/(n-1) not 1/n"
In the markscheme.......They just use 1/n, no mention of using the sample formula at all?!?!
Can someone please tell me what I did wrong? Or are they just stupid?
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S1 Markschemes - SO ANNOYING! watch
- 09-06-2004 21:52
- 09-06-2004 21:58
I just noticed that underneath it does say (NB using n-1 gives...)
but still. i think the *right* way (the sample one!) should be the proper answer, and they put the not-quite-right one underneath!
- 10-06-2004 16:15
Not on syllabus = you don't have to use it
- 10-06-2004 17:14
Well, ok, it does just say "variance" on the markscheme. It doesn't specify what kind.
But it is (the sample one) in the Edexcel textbook.. and both are in the formula book