Answer:
The sum is 1090
Explanation:
S=7+12+17+22+...+102 ---> reason=5
We define the values, before starting:
Ratio = r , Term n = Tn , Term number = n , Term one = T1
To do this we first find the term number of 102, with the following formula:
Tn = t1 + (n - 1) r
102 = 7 + (n - 1) 5
102 = 7 + 5n - 5
102 = 5n + 2
100 = 5n
20 = n
Then we realize that 102 is the term N°20, now what we have to do is find the sum of the arithmetic series, with the following values and the following formula:
t1 = 7 , tn = 102 , n = 20
S = (
) . n
S = (
) . 20
S = 109 . 10
S = 1090