In one or two sentences

MATHEMATICS · Subjective · AP · AP Statistics · Probability Random Variables Distributions · Probability Random Variables Distributions

Problem

In one or two sentences, explain what the denominator

\sum_i P(E_i)\,P(A\mid E_i)

represents when calculating

P(E_k\mid A)

for events

\{E_i\}

that form a partition of the sample space.