To find the percent of increase take the difference of the two divided by the original. (62-55)/55 = .12727272727. So 13% if they want you to round to the nearest percent.
I'm guessing the sum is supposed to be

Split the summand into partial fractions:


If
, then

If
, then

This means

Consider the
th partial sum of the series:

The sum telescopes so that

and as
, the second term vanishes and leaves us with

Check the picture below.
make sure your calculator is in Degree mode.