Question 759558
Similar Triangles
Height of Lampost/Jim's height
= Distance between Jim and lampost + x (shadow)/ Distance between
Jim and lampost

    15/5.5 = 3 + x/x
  Cross multiply
      15x = 5.5(3 + x)
      15x = 16.5 + 5.5x
   15x - 5.5x = 16.5
          9.5x = 16.5
             x = 1.74ft
His shadow is 1.74ft long
Hope this helps.
:-)