Question

A worker is paid $0.05 on the first day, $0.10 on the second day, $0.20 on the third day, $0.40 on the fourth day, and so on. How much money (rounded to the nearest cent) in total does the worker earn after working 21 days?

Answer 1

This is a geometric sequence with a common ratio of 2

an = a1 * r^(n - 1)
n = term to find = 21
a1 = first term = 0.05
r = common ratio = 2
now we sub
a21 = 0.05 * 2^(21 - 1)
a21 = 0.05 * 2^20
a21 = 0.05 * 1048576
a21 = 52428.80 <==== after working 21 days