Question 885100
To solve this we set up a proportion between heights of things and the shadows they cast.  We know that the person is 5.5 feet tall and casts an 8 foot shadow so that's our first side of our proportion.  Now we want to compare that to the tree which is x feet long and casts a 18 foot shadow.  So we get the following proportion:<br>

{{{5.5/8 = x/18}}}<br>

Now we cross multiply and solve for x.<br>

18(5.5)=8x
99 = 8x
99/8 = x
12.4 feet = x