The thickness of the boundary layer at this point is

Question

A fluid is flowing over a flat plate. At distance of 8 cm from the leading edge, the Reynolds number is found to be 25600. The thickness of the boundary layer at this point is                                       

(a) 1.5 mm                   (b) 2.5 mm      

(c) 4.0 mm                   (d) 5.0 mm