Question

Bamboo plants grow rapidly. A bamboo plant is 130 inches tall. Tomorrow it will be 143 inches tall, the next day it will be 156 inches tall, and on the next day it will be 169 inches tall. Write an explicit formula to represent the height of the bamboo plant as an arithmetic sequence. How tall will the plant be in 13 days?
A. A(n) = 130 + 13n; 286 inches

B. A(n) = 130 + (n-1)13; 286 inches

C. A(n) = 130 + (n-1)13; 299 inches

D. A(n) = 130 + 13n; 299 inches <--------

Answer 1

Your choice of answer D is correct.

_____

When the number of days is zero, the height is 130 inches. This eliminates choices B and C. Evaluating the expression for n=13 gives

... 130 + 13×13 = 130 + 169 = 299 . . . . . corresponding to answer D.