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?

Question

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?

miracrown · Answer

What have you got so far?

anonymous · Answer

nothing...i dont understand it at all

miracrown · Answer

OK.
Let me ask you; what formula have you seen for correlation in class?

miracrown · Answer

or have you seen nothing as yet?

anonymous · Answer

i havent seen the formula yet . I'm ahead of the class..

miracrown · Answer

Hold on while I blend my numbers...

miracrown · Answer

OK
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 :)

miracrown · Answer

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%! so here is our answer <<<