How to find the mean of a histogram (parent needs help on son's behalf.

UOcUK Poopscoop · 3 Jan 2013 at 20:35

My lad is in year 11 and has this question on MyMaths. For the life of me I cant work out how they get 16.75. Ive googled but Im still not getting that figure using the methods Ive found.

Can one of you guys take pity on this 44 year old trying to help his son how to solve this "riddle"?

Many thanks guys!

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Incinerat0r · 3 Jan 2013 at 20:41

Take the midpoint of each group and times it by the frequency and add each together, divide sum of results by total frequency

UOcUK Poopscoop · 3 Jan 2013 at 20:55

OK...

Im still doing it wrong, but where? Thanks for help!

I am using:

2.5x14 + 7.5x12 + 15x18 + 27.5x3 + 42.5x4= 470

Incinerat0r · 3 Jan 2013 at 20:57

Use the frequency in the table, ignore the graph. So 2.5 x 70, 7.5 x 60 and so on

UOcUK Poopscoop · 3 Jan 2013 at 21:03

Incinerat0r said:
Use the frequency in the table, ignore the graph. So 2.5 x 70, 7.5 x 60 and so on

Got it, finally! :eek:

Thanks SO much for taking the time to reply. Really appreciated.

estebanrey · 3 Jan 2013 at 21:04

steve9098 · 4 Jan 2013 at 01:18

Oh Mymaths, I know your pain...

Destination · 4 Jan 2013 at 07:48

In the first table why are some pf the colmns three times as wide as others?
Ignoring the op q's it has been answered by why is that first graph so odd?

Name · 4 Jan 2013 at 08:43

Maths was never that confusing when i did it! good lord.

Wait, it probably was i just cant remember!

One More Solo · 4 Jan 2013 at 08:47

Hikari Kisugi said:
In the first table why are some pf the colmns three times as wide as others?
Ignoring the op q's it has been answered by why is that first graph so odd?

So the graph corresponds to the scale on the x axis, not all the groups have the same range.