Question

In 2010 an item costs $9.00. The price increases by 1.5% each year. How much will it be in 2020?

Answer 1

The term is actually forming an AP.

On 2010 = $9 = a

`(1.5)/(100) * 9 \\ = (13.5)/(100) \\ = 0.135`

d = $0.135

now on 2020, that's 10 years after 2010.

n = 10

`an = a + (n - 1)d \\ = 9 + (10 - 1)0.135 \\ 9 + 9(0.135) \\ = 9 + 1.215 \\ = 10.215`

THE FINAL ANSWER - $10.125

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• there might be another ways to solve this problem, but the simplest way is AP.