Question 325534
Missy made her annual income of RM25,710 in the fourth year and RM38,560 in the ninth year working in SIMEC Ltd. Assuming that her annual income behave like an arithmethic sequence:
a. How much was her annual income in the first year


Since this is an arithmetic sequence, we can determine the difference between the years by subtracting year 4's amount from year 9's amount, and then divide this amount by 5 (the difference between the years), or,


{{{(38560 - 25710)/5}}}  =  {{{12850/5}}} = $2,570


Since year 1 to year 4 covers 3 years, we multiply $2,570 by 3 and subtract this result from year 4's amount. This gives us: $25,710 - $7,710 = $18,000.


This means that her annual income in the first year was: ${{{highlight_green(18000)}}}.


This first year annual income could have also been found using the arithmetic progression formula, {{{t[n] = t[1] + (n - 1)d}}}, where {{{t[n]}}} is the term, "n" is the term number, {{{t[1]}}} is the first term, and d is the common difference.