What is the sum of the first 19 terms of an arithmetic series with a rate of increase of 7 and a7 = 46?

A. 1,197

B. 1,273

C. 1,373

D. 1,423

E. 1,327

Calculate for the first term of the series

an = (a1) x (n - 1) x d

Using the value of a7 = 46 and the rate of increase

46 = (a1) x (7 - 1) x 7

The value of a1 is 4.

Solving for the sum of 19 terms,

Sn = (n/2) x (2a1 + (n - 1) x d)

Substituting,

Sn = (19/2) x ((2) (4) + 18 x 7)

The sum of the first 19 terms is 1,273. Therefore, the answer is letter B.