Question

A part is made from solid bras rod of 38 mm diameter and length 25 mm. The machining time taken to finish the part is 90 minutes and labour rate is Rs. 2 per hour. Factory overheads are 50% of direct labour cost. The density of material is 8.6 gm per cubic cm and it cost Rs. 1.625 per newton. The factory cost of the part will be
1. Rs. 8.40
2. Rs. 4.80
3. Rs. 14.80
4. Rs. 18.40

Answer 1

Correct Answer - Option 1 : Rs. 8.40

Concept:

Factory cost of the part will be

Material Cost + Labour Cost + Overhead cost

Calculation:

Let us find the costs one after another

Density of the material = 8.6 gm/cm³ = 8.6 × 10^-3 kg/cm³ and the cost is Rs. 1.625/N, D = 38 mm, L = 25 mm, Labour rate = 2/hr, Overhead cost = 0.5 × Labour Cost

∴ The material cost = weight of the material × cost/weight

Weight of the material = ρ × V × g

\(V = \frac{\pi }{4}{D^2} \times L = \frac{\pi }{4} \times {38^2} \times 25 = 28352.87\;m{m^3} = 28.3\;c{m^3}\)

Now weight = 8.6 × 10^-3 × 28.3 × 9.81 = 2.38 N

∴ the material cost = 2.38 × 1.625 = 3.86 Rs.

Labour cost = Machining time × labour rate/ time

Labour cost = 1.5 × 2 = 3 Rs.

Overhead cost = 3 × 0.5 = 1.5 Rs.

Now total cost

C = 3.86 + 3 + 1.5 = 8.36 Rs.