For random variable problem 71: A discrete variable has PMF P(X=k)=c⋅2−kP(X=k) = c \cdot 2^{-k}P(X=k)=c⋅2−k for k=1,2,3,…k = 1, 2, 3, \ldotsk=1,2,3,…. Find ccc.
12\frac{1}{2}21
111
222
14\frac{1}{4}41