Statistics AS maths help Watch

juicedesuccess
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Hi there - could someone please help me with the following question:

"A group of 60 children were each asked to choose an integer value between 1 and 9 inclusive. Their choices are summarised in the table below:

Value Chosen | Number of children
1 | 3
2 | 4
3 | 5
4 | 10
5 | 12
6 | 13
7 | 7
8 | 4
9 | 2

Calculate the mean.


I would like to know why the mean is worked out as [sum of x * Frequency] / frequency and not [sum of x]/n ... I thought that this looked like discrete data and not continuous/ grouped data so can't understand why we are using the former formula... Sorry if I'm missing something basic. Thanks again
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phishingrhod
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number of children = f, so it needs to be sum of xf divided by the sum of f, that's as well as I can explain it, sorry if it isn't much use
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juicedesuccess
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(Original post by phishingrhod)
number of children = f, so it needs to be sum of xf divided by the sum of f, that's as well as I can explain it, sorry if it isn't much use
Hi - thanks so much for your quick response. Just wondering though- which wouldn't it be 60/9 = 6.7 (1dp)? just a tad confused as the stats book suggests you should only use the xf/f formula for continuous/ grouped data - and this is discrete data - unless I'm missing something basic?
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phishingrhod
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tbh, I'm not sure as to why, but now whenever I see this sort of question, I go for the xf/f by instinct, but I suppose it's the amount (/frequency) of children picking a certain number, which means that the mean number chosen would be 303/60=5.05

Best bet is, if a particular group of people are CHOOSING something, take what they choose as being x, and the number of times that x is chosen is f, that's what seems to work for me

sorry if this hasn't been much help, again
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juicedesuccess
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(Original post by phishingrhod)
tbh, I'm not sure as to why, but now whenever I see this sort of question, I go for the xf/f by instinct, but I suppose it's the amount (/frequency) of children picking a certain number, which means that the mean number chosen would be 303/60=5.05

Best bet is, if a particular group of people are CHOOSING something, take what they choose as being x, and the number of times that x is chosen is f, that's what seems to work for me

sorry if this hasn't been much help, again
Great, thank you so much
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