Y7 Maths homework - help! Mean and Mode

[jodee]

DS loathes maths and homework is a nightmare. Anyway, I am trying to keep my cool with him, me being angry and irritated doesn't help. We use MyMaths, I do the revision first so I can try and help him.

I should be able to do this but am stumped - we can work out the average of a set of numbers ok, but I have a question where we have the Mean number already and have to fill in the value - I'm sure it's simple but the question goes along the lines of ...

Johnny caught 8 fish and the mean weight of the fish was X.

He forgot to weigh the 8th fish, but the first 7 weighed a,b,c,d,e,f,g.

What was the weight of the 8th fish?

Can anyone tell me the method? Also, anyone recommend ways to help a frustrated 12 year old boy (Carold Vorderman??) DS struggles with Attention Deficit.

Thanks in advance.

Mean = sum / number

So multiply mean by 8 to get sum of all 8 numbers.

Then take away the sum of the other 7 numbers.

Got it, thanks so much! No I just have to try and help DS 'get it'

Any suggestions for helping DS generally, anyone?

Hey Diddle Diddle,
the median's the middle
you add and divide for the mean
the mode is the number that shows up the most
and the range is the difference between

Snowball 3 posted this a while back it really helped my children

I always remember which is which because mode means fashion (in French - think a la mode) and so the mode is the most fashionable number ie the one there is the most of.

The mean is what msot grown ups think of when we say "the average" ie add them all up and divid by how many. HTH

Thanks again, and that rhyme will come in handy, I'm sure.