Question

A. An equipment installation job in the completion stage can be completed in 40 days of 8 hour day work, with 40 men working. With the contract expiring in 30 days, the mechanical engineer contractor decided to add 10 men on the job, overtime not being permitted. If the liquidated damages is $2,000 per day of delay, and the men are paid $80 per day, will the engineer be able to complete the job on time? How much should he save money with the addition of workers?

B. An 8-m wide concrete road pavement 500 meters long is desired to be constructed over a well-compacted gravel road, together with the necessary concrete curbs and gutters on both sides. In order to put the subgrade on an even level grade, a 500 cu. m. of sand filling is necessary, over which the 10-inch concrete pavement will be placed. How much will the project cost, allowing for 15% contingency and assuming the following data?
(a.) Sand fill, including rolling and watering – $10 per cu.m.
(b.) Concrete curb and gutter (labor and materials) – $12 per linear meter
(c.) Concrete pavement, 10 in. thick (labor and materials), including curing – $22 per sq.m.

C. Seawater contains 2.1 pounds of magnesium per ton. By using the processing method A, 85% of the metal can be recovered at a cost of $3.25 per ton of water pumped and processed. If process B is used only 70% of the available metal is recovered, at a cost of only $2.60 per ton of water pumped and processed. The two processes are substantially equal as to investment costs and time requirements. If the extracted material can be sold for $2.40 per pound, which processing method should be used?

Answer 1

Answer:

A. 40 men can complete a job in 40 days means each worker per day is completing 1/(40*40)=1/1600 of job.

50 men can complete this job in 32 days(50*32=1600).

But there is penalty of $2000 per day. So if 10 extra workers are not employed then the penalty would have been $20,000. With employing 10 additional workers penalty is $4000 for 2 days delay.

With addition of 10 workers, additional workers are paid $80*32*10=$25600. While saving of 8 days of work of 40 workers=$80*40*8=$25600. So extra cost incurred by employing extra labor is saved by reducing work days by 8.

Engineer was not able to complete job in 30 days(completed in 32 days). Employing extra labor saved $16000 of penalty($20000-$4000).

B.

(a) Cost of sandfill= $10/cum*500 cum.=$5000.

(b) Concrete curb and gutter=$12/linear metre*500 metre=$6000.

(c) Concrete pavement 10 inch thick=$22/sqm.*4000sqm.(8m wide*500m long)=$88000.

Total cost of project=$101000+15%of 101000 for contingency=$116150.

C.

Price of magnesium extracted using method A=2.1 pound*85%*$2.40=$4.284.

Cost of using method A=$3.25 per ton.

Profit by using Method A=$4.284-$3.25=$1.034.

Price of magnesium extracted using method B=2.1 pound*70%*$2.40=$3.528

Cost of using method B=$ 2.60 per ton.

Profit by using method B=$3.528-$2.6=$0.928.

Method A should be used because it is giving higher profit.