D(1-1/4)
=3/4d
3/4d represents the money saved on a pillow
5 to the 4th power would be one way
Answer:
6561 / 128
Step-by-step explanation:
The nth term of a geometric sequence is:
a = a₁ (r)ⁿ⁻¹
The first term is 3, and the fourth term is 81/8.
81/8 = 3 (r)⁴⁻¹
27/8 = r³
r = 3/2
The eighth term is therefore:
a = 3 (3/2)⁸⁻¹
a = 6561 / 128