First of all, we need to convert 2 1/3 yards into feet. 2 1/3 = 7/3 yard. Since a yard has 3 feet, we multiply this by 3 and we get that 2 1/3 yards equal 7 feet. Now we move on to proportions. If the shadow of a boy 6 feet tall produces the shadow of 3 feet, we need to see which height can produce a shadow of 7 feet.
