SOLUTION: The hourly wage of some automobile plan workers went from 7.90 to 13.35 in 9 years annual raises if their wages are growing exponentially what will be their hourly wage in 3 more

In this problem, we have given the exponential raise for 9 years,
and the question asks about this exponential function 3 years later.


In order for to make calculations minimal, I will apply a trick: I will find first 
the coefficient of growth in 3 years, and then will use it to answer the question.


So, let R be the coefficient of growth in 3 year. Then I can write this equation

    13.35 = ,

or

     = ,

    1.689873418 = 

    R =  = 1.191108685.


Having it, the answer to the problem's question is in one line:

    their hourly wage in 3 more year is  13.35*1.191108685 = 15.90  (rounded as requested).    ANSWER