Math Is Fun Forum

I think you have to take each pair of Score and Sample size and multiply them, and then add these together to get a total,
then divide by the total sample size for all of the rows you have added:

eg. (3.83 x 521) + ..... + ...... I have just given the first row of the scores x sample sizes (I won't add all of them because there are a lot - and also that is your job)....
Then add 521 + 806 + ..... and get the sample size total

Remember to treat each year separately of course for both totals in each case.
(Similar principle for the top table except that they are not years, and similar I think for the percentages,
just treat them like scores - multiply them by the sample sizes in each row - then sum them - then divide by the total sample size.
I notice that the total sample sizes are there already and that the averages are already given.)