Explanation :-

Bulldozer,

• It is a earth moving equipment.
• It is primarily used for earth moving, leveling, grading, pushing, clearing and scrubbing of the worksite.

Solution :-

If project is behind scheduled time ⇒ Slack Time will be Negative

Here,

Completion (scheduled) time = 10 weeks

Earliest expected time = 15 weeks

So, project is behind scheduled time, hence slack time will be negative.

Slack time = Earliest expected time - Scheduled completion time

Slack time = 15 - 10 = 5 weeks (Negative)

Calculation :-

In PERT analysis,

Expected time of an activity (te),

= (to + 4tm + tp) / 6

= (7 + 4 x 10 + 19) / 6

= 66/6

= 11 days

Explanation :-

(i) A head event is the one which marks the completion of an activity

(ii) A tail event is the one which marks the beginning of an activity

Explanation :-

In PERT analysis,

• Whole project duration follows Normal distribution.
• Whereas individual activities follows Beta distribution.

Solution :-

Area of plaster = 100 m²

Thickness of plaster = 12 mm = 0.012 m

Volume of wet mortar = 100 × 0.012 = 1.2 m³

Dry volume = 1.2 × 1.25 = 1.5 m³ (∴ increased by 25 %)

Now, volume is increased by 30 % due to uneven surface,

V = 1.5 × 1.3 = 1.95 m³

Volume of cement required,

= (1/5) × 1.95     (∴ Cement: Sand = 1:4)

= 0.39 m³

Density of cement = 1440 kg/m³

Weight of cement required,

= Volume of cement × Density of cement

= 0.39 × 1440

= 561.6 kg

No. of Cement bags required,

= 561.6/50     (∴ 1 bag = 50 kg)

= 11.232

≈ 12 Bags

Explanation :-

Annual Depreciation,

= (Equipment cost - Salvage value)/Life of equipment

= (25 - 5)/5

= 4 Lakhs

Explanation :-

Earnest Money Deposit (EMD) : 1 - 2 % of estimated cost of the work

Security Deposit (SD) : 5 - 10 % of estimated cost of the work

Explanation :-

Interfering Float :

• Total Float - Free Float

Total Float :

• Free Float + Interfering Float
• Independent float + Tail slack+ Interfering Float
• Time by which an activity may be delayed or extended without affecting the total project duration.

Free Float :

• Independent float + Tail slack
• Time by which an activity may be delayed or extended without delaying the start of any succeeding activity.

Independent Float :

• Time by which an activity may be delayed or extended without affecting the preceding or succeeding activities in any way.

Solution :-

Uncertainty and certainty of any activity or any project is determined by its variance (V).

V (↑) ⇒ Uncertainty (↑) ⇒ Certainty (↓)

V (↓) ⇒ Uncertainty (↓) ⇒ Certainty (↑)

Variance (V) = [(tp - t0)/6]²

Contractor A :

Variance (V) = [(13 - 5)/6]² = 1.33²

Contractor B :

Variance (V) = [(12 - 6)/6]² = 1²

Contractor C :

Variance (V) = [(14 - 5)/6]² = 1.5²

Contractor D :

Variance (V) = [(13 - 4)/6]² = 1.5²

So, Contractor B is more certain about completing job in time.

Shortcut :-

tp - t0 (↓) ⇒ Certainty (↑)

13 - 5 = 8

12 - 6 = 6 (↓) ⇒ Certainty (↑)

14 - 5 = 9

13 - 4 = 9