Example

Example: The Multiplier Effect as an Infinite Geometric Series

A government gives a $1,000 tax rebate to each household. Statistics indicate that each recipient will spend 80% of the money on goods and services, and each subsequent recipient of that spending will also spend 80% of what they receive. What is the total effect of the rebate on the economy?

Each round of spending forms a geometric pattern:

1000+1000(0.8)+1000(0.8)2+1000 + 1000(0.8) + 1000(0.8)^2 + \dots

This is an infinite geometric series with a1=1000a_1 = 1000 and r=0.8r = 0.8. Because r=0.8<1|r| = 0.8 < 1, the series converges and its sum can be computed:

S=a11r=100010.8=10000.2=5000S = \frac{a_1}{1 - r} = \frac{1000}{1 - 0.8} = \frac{1000}{0.2} = 5000

The total economic impact of the $1,000 rebate is $5,000 per household. This result — known as the multiplier effect — shows that when each recipient re-spends a fixed percentage of what they receive, the cumulative impact on the economy is a multiple of the original amount. The infinite geometric series formula provides a concise way to calculate that total.

0

1

Updated 2026-05-25

Contributors are:

Who are from:

Tags

OpenStax

Intermediate Algebra @ OpenStax

Ch.12 Sequences, Series and Binomial Theorem - Intermediate Algebra @ OpenStax

Algebra