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

[UOcUK Poopscoop]

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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[UOcUK Poopscoop]

OK...

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

I am using:

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

 

[UOcUK Poopscoop]

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

Got it, finally!

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