Five persons A, B, C, D, E are contesting  an election in which 3 persons are to be elected. If C is elected unanimously, the probability that D gets elected is 

Five persons A, B, C, D, E are contesting  an election in which 3 persons are to be elected. 

$\mathrm{M}=\mathrm{C} \mathrm{is} \mathrm{selected} \mathrm{unanimously}$

$\mathrm{n}\left(\mathrm{M}\right)= \mathrm{selecting} \mathrm{two} \mathrm{persons} \mathrm{from} \mathrm{A},\mathrm{B},\mathrm{D},\mathrm{E}{=}^4{\mathrm{C}}_2=6$

$N=D is selected$

$n\left(M\cap N\right)= selecting one person from A,B,E={ }^3{C}_1$

$P\left(N/M\right)=\frac{n\left(M\cap N\right)}{n\left(M\right)}=\frac{3}{6}=\frac{1}{2}$