The monthly salary S( t ) in dollars for a dock worker shown above has the following cubic model.
S(t)=0.182t37.55t2+101.2t+990\displaystyle {S}{\left({t}\right)}={0.182}{t}^{{3}}-{7.55}{t}^{{2}}+{101.2}{t}+{990} where t is the number of years after 1980
Interpret S( 1998 ) = 1426.82

Interpret S(1998)=6.3\displaystyle {S}'{\left({1998}\right)}={6.3}