retired_susan mcdonald

these

I half remember how to do them but not really. I'm so so so rusty at maths. So yeah could you tell me how you do it thanks. x

retired_amadhani

can't you just have one big "mikey g is thick" thread all to yourself?

retired_shelwill

For the mean average, take x as the mid-point of the band and multiply by the frequency, then divide by the total

so q.18 is ((2.5*2)+(7.5*6)+(12.5*2)+(17.5*5))/15

Cant remember how quartiles work.

retired_susan mcdonald

yeah probs is needed.

How weird though, 3 years ago i was doing A Level maths stuff, now I can't even do GCSE stuff. how rubbish

retired_susan mcdonald

yeah that's how i thought you did that. It's the median and the quartiles that screws me

retired_lbherrera

I could have sworn I did this in another thread yesterday which you asked?

retired_nini59

find the total frequency and divide by 4 to find the number you need for the quartiles I think, so for 1 it's 15/4 = 3.75, then you find where this number would occur, 3 is the first range, and so it's 0.75 into the 2nd range, as there's 5 in the second range then you take the midpoint, 7.5, and divide by 5 and multiply by 0.75 = 1.125, and add this onto the lower boundary, so it's 6.125

sorry it that's confusing, for the 3rd quartile it's pretty similar, just divide the total frequency by 4/3, then work out where this number would lie, and subtract the first quartile for the interquartile range.

retired_susan mcdonald

ok the first bit makes complete sense, cheers. and so does the second, cheers.

retired_irenenieves

Or, on the flipside, making me look like a dumbass if they're really useful

retired_irenenieves

What possible use are those equations to the world?!

Apart from looking like a smart ass?