Question

Two coal loading machines each working 12 hours per day for 8 days handles 9 tons of coal with an efficiency of 90%. While 3 other coal loading machines of an efficiency of 80% set to handle 12 tons of coal in 6 days. Find how many hours per day each should work?

Answer 1

Ans. (3) 16 h/day
According to question
M1 × D1 × W1 = M2 × D2 × T2 × W1
2 × 12 × 8 × 12000 × 0.9 = 3 × 6 × X × 9000 × 0.8
=> X = 2 x 12 x 8 x 12000 x 0.9/3 x 6 x 9000 x 0.8
= 16h/day

Answer 2

Answer:

16 hours

Explanation:

Let x hour per day, each group should work.

In first group -

Machine = 2, Hours = 12, Days = 8 Coal = 9 tons and efficiency = 90%

In second group -

Machine = 3, Hours = x, Days = 6 Coal = 12 tons and efficiency = 80%

Therefore according to the equation -

= M1 × D1 × T1 ×W1 = M2 × D2 × T2 × W1

= 2 × 12 × 8 × 12000 × 0.9 = 3 × 6 × X × 9000 × 0.8

= X = 2 x 12 x 8 x 12000 x 0.9/3 x 6 x 9000 x 0.8

= 16h/day

Thus, the machine needs to work 16 hours per day.