A cantilever beam of length l is subjected to a concentrated load P at a distance of l /3 from the free end. What is the deflection of the free end of the beam? (EI is the flexural rigidity)
(a)$\frac{2Pl^{3}}{81EI}$ (b)$\frac{3Pl^{3}}{81EI}$
(c)$\frac{14Pl^{3}}{81EI}$ (d)$\frac{15Pl^{3}}{81EI}$