D1 June 2015 Q7

Notes

a1B1: Any two of the four arcs (E, F, I or the dummy) drawn correctly (from correct vertex to correct vertex) – activities must be labelled with the correct letter (but condone no weights or arrows) and the dummy must be shown as a dashed line (but condone no arrow)

a2B1: All four arcs (E, F, I and the dummy) drawn correctly – must be labelled with the correct letter (but condone no weight or arrows) and the dummy must be shown as a dashed line (but condone no arrow)

a3B1: CAO – all three activities (E, F and I) and the one dummy drawn correctly – activities must be labelled with the correct letter and the activities and dummy must have the correct arrows (do check carefully that all arrows are present) but condone lack of (or incorrect) weights on the activity arcs

Notes

b1M1: All top boxes complete (condone lack of 0 for the M mark only), values generally increasing in the direction of the arrows (‘left to right’), condone one ‘rogue’ value (if values do not increase in the direction of the arrows then if one value is ignored and the remaining values do increase in the direction of the arrows then this is considered to be a single rogue value). Note that all values in the top boxes could be incorrect but it can still score the M mark if the values are increasing in the way stated above – this mark is dependent on the first mark having being awarded in (a)

b1A1: CAO – all values correct in the top boxes – this mark is dependent on the first two marks having being awarded in (a)

b2M1: All bottom boxes complete (condone lack of 39 and/or 0 for the M mark only), values generally decreasing in the opposite direction of the arrows (‘right to left’), condone one ‘rogue’ – this mark is dependent on the first mark having being awarded in (a)

b2A1: CAO – all values correct in the bottom boxes – this mark is dependent on the first two marks having being awarded in (a)

Notes

c1M1: Attempt to find lower bound: (a value in the interval [80 – 104] / their finish time) or (sum of the activities / their finish time) or (as a minimum) an awrt 2.4

c1A1: CSO – either a correct calculation seen or awrt 2.4 then 3. An answer of 3 with no working scores M0A0

Notes

d1M1: Not a cascade (Gantt) chart. 4 ‘workers’ used at most and at least 8 activities placed

d1A1: The critical (C, H, J, L) activities and A, B and D correct. A must be completed by its late finish time (22), B must be completed by its late finish time (13) and D must start after A and finish before its late finish time (32)

Now check the last 5 activities – the last two marks are for E, F, G, I and K only

First check that there are only three workers and that all 12 activities are present (just once)

Then check precedences (see table below) – each row of the table could give rise to 1 error only in precedences

Finally check the length of each activity and the time interval in which the activity must take place (interval is inclusive)

d2A1: 3 workers. All 12 activities present (just once). Condone one error either precedence or time interval or activity length, on activities E, F, G, I and K only (note: one activity could have more than one error, for example, activity G could have an error in duration and an error in IPA – this is two errors not one)

d3A1: 3 workers. All 12 activities present (just once). No errors on activities E, F, G, I and K