write the sum using summation notation
1+6+13+22+33
N
Σ = Xi = X1 + X2 + X3... + XN
i=1
5
Σ = 1 + 6 + 13 + 22 + 33 = 75
i=1
I got this by looking up "summation notation" on
Google to get:
http://www.psychstat.missouristate.edu/introbook/sbk12m.htm
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.