We know the first term must be: 100
Last term must be: 300
Number of terms = (300 - 100) / 2 + 1 = 200/2 + 1 = 100 + 1 = 101
Now use the arithmetic progression sum formula: [tex]S= \frac{n}{2}(a+l) [/tex]
where:
n = number of terms = 101
a = 1st term = 100
l = last term = 300
Therefore: S = [tex] \frac{101}{2}(100+300)= \frac{101}{2}*400=101*200=20200[/tex]
