1. If 100 is saved on October 1, 150 on October 2, 200 on October 3, and so on, how much is saved during October?

2. A Ping-Pong ball is dropped from a height of 16 ft and always rebounds 1/4 of the distance of the previous fall.
a. What distance does it rebound the 6th time?
b. What is the total distance the ball has travelled after this time?

#1 You have an A.P. with

a = 100
d = 50
S31 = 31/2(2*100 + 30*50)

#2 You have a G.P. with
a = 16
r = 1/4
So, find T7 and 2S6-16+T7
the strange sum is because you have just a drop on T1 and a bounce on T7, and not 7 complete round trips