Question

Due to erosion, the height of Math Mountain decreases at a rate of 2% every century.

If the the mountain was 18,000 ft in 2005, how tall was the mountain in 1505?

Answer 1

we can model this as \(18,000\times (.98)^t\) where \(t\) is time in centuries

Answer 2

that is because reducing a number by 2% is the same as multiplying it by \(.98\)

Answer 3

since 1505 is 5 centuries BEFORE 2005, replace \(t\) by \(-5\) and see what you get

Answer 4

i get 19,913 rounded
http://www.wolframalpha.com/input/?i=18000%28.98%29^-5