In PERT analysis, the expected time to complete an activity is computed from the three time estimates : a most likely time (m), an optimistic time (a), and pessimistic time (b) using the expression

A. $$\frac{{\left( {a + 4m + b} \right)}}{6}$$

B. $$\frac{{\left( {4a + m + b} \right)}}{6}$$

C. $$\frac{{\left( {a + m + 4b} \right)}}{6}$$

D. $$\frac{{\left( {a + m + b} \right)}}{3}$$

Answer: Option A