Expected Times

Expected-Time Formula

The PERT expected time is exact weighted arithmetic.

highlighted = computed this step

Formula pieces

PERT uses optimistic 1, most likely 2, and pessimistic 3 for activity A.

oA,mA,pAo_A,m_A,p_A
Expected activity timesExpected times are recomputed from the three estimates.expected activity timesoptimisticmost likelypessimisticexpectedA1232B2343C1257/3D2222

Most likely weight

The most likely estimate gets weight 4 in the expected-time arithmetic.

middle weight=4\text{middle weight}=4
Expected activity timesExpected times are recomputed from the three estimates.expected activity timesoptimisticmost likelypessimisticexpectedA1232B2343C1257/3D2222

Divide by six

The weighted sum is divided by 6.

denominator=6\text{denominator}=6
Expected activity timesExpected times are recomputed from the three estimates.expected activity timesoptimisticmost likelypessimisticexpectedA1232B2343C1257/3D2222

A expected time

Activity A's expected time is 2.

EA=2E_A=2
Expected activity timesExpected times are recomputed from the three estimates.expected activity timesoptimisticmost likelypessimisticexpectedA1232B2343C1257/3D2222