Logs are stacked in a pile where the bottom row has 24 logs, the next row has 23 logs, the following row has 22 logs and the pattern continues until the top row has 15 logs.

Question

Logs are stacked in a pile where the bottom row has 24 logs, the next row has 23 logs, the following row has 22 logs and the pattern continues until the top row has 15 logs. How many logs are in the pile?

______ logs

Answer 1

Deteremine the number of rows

15 = 24 + (n - 1)(-1)

Use the n from above in

S_n = (n / 2)(24 + 15)