Question

Heavy rain caused a river to rise. The river rose three inches the first day, and each additional day it rose twice as much as the previous day. How much did the river rise in five days?

a.
102 in
c.
93 in
b.
145 in
d.
15 in

Answer 1

c 93 in

Step-by-step explanation

a = 3

r = 2

Explanation:

Answer 2

c 93 in

Explanation:

This is a Geometric sequence with:

a = 3

r = 2

We need S5

S5 = 3(2⁵ - 1)/(2 - 1)

= 93