Given parameters:
Height of Kevin = 3ft
Height of Bob = 2.5ft
Hieght of Kevin's shadow = 5ft
Unknown:
Length of Bob's shadow = ?
We can simply set up simple ratio to solve this problem.
The ratio of Kevin's height to Bob's height is 3 : 2.5
The ratio of their shadow should also be 5: Bob's shadow height
Equating the two of them should give a fairly constant ratio;
[tex]\frac{3}{2.5} = \frac{5}{Bob}[/tex]
3Bob = 5 x 2.5
Bob's shadow height = [tex]\frac{5 x 2.5}{3}[/tex] = 4.2ft
The height of Bob's shadow is 4.2ft.