The correlation coefficient r between a child’s age, x, and the number of minutes spent doing homework each day, y, is 0.694. what percent of the variation in the number of minutes doing homework cannot be explained by differences in the children’s ages?

So, they are looking for the percentage that is NOT explained... Well, given the r we can find the percentage that IS explained by it first. That's given by r^2.

Now - let's take the square of r it gives me .481636. That means that about 48% IS explained. Therefore, the part that cannot be explained must be the missing part (out of 100% so 100% - 48.1636% should be it :)

So 100% - 48.1636% = 0.518364 and we want to round that off to three decimal places which will give us 0.518... and then we could convert that to a percent for the final. So 0.518 as a percentage is 51.8%! s