Let S_{n} be the sum of the first n term of an arithmetic sequence that has a common difference of 2 . The quotient \dfrac{S_{3 n}}{S_{n}} does not depend on n. What is S_{20} ?
Answer Choices
A. 340
B. 360
C. 380
D. 400
E. 420
Let S_{n} be the sum of the first n term of an arithmetic sequence that has a common difference of 2 . The quotient \dfrac{S_{3 n}}{S_{n}} does not depend on n. What is S_{20} ?
Answer Choices
A. 340
B. 360
C. 380
D. 400
E. 420