An employee starts on a salary of $26,750 and receives a 1.6% annual raise. What are the total earnings at the end of 5 years?

1. Each year the salary is 101.6% of the year before, so the common ratio is 1.016. 2. The first year's pay is 26,750 and the total runs over 5 years, so n = 5. 3. Substitute into S_n = a_1(1 - r^n)/(1 - r) to get S_5 = 26,750(1 - 1.016^5)/(1 - 1.016). 4. Raising 1.016 to the fifth power gives about 1.0826. 5. The quotient (1 - 1.0826)/(1 - 1.016) is about 5.163. 6. Multiplying gives about 138,099. 7. Multiplying 26,750 by 5 with no raises at all gives 133,750, which is the floor rather than the answer. _Source: OpenStax Algebra and Trigonometry (CC BY 4.0), Ch 13 "Sequences, Probability and Counting Theory", section 13.4 Series and Their Notations_