Question

Difficulty: HardUnit Conversions

A manufacturing plant uses a machine lubricant at a constant rate of 0.080.08 fluid ounces per second of operation. The plant operates the machinery for 88 hours per day, 55 days a week. The lubricant is purchased in drums, where each drum contains 1515 gallons of lubricant. How many drums of lubricant does the plant use in a period of 55 weeks? (Note: 1 gallon=128 fluid ounces1\text{ gallon} = 128\text{ fluid ounces})

Answer: 30 drums

Answer

The plant uses 30 drums of lubricant in 5 weeks.
To find the number of drums, calculate the total seconds of operation: 5 weeks * 5 days/week * 8 hours/day * 3,600 seconds/hour = 720,000 seconds. Multiply this by the consumption rate of 0.08 fluid ounces/second to get 57,600 fluid ounces. Convert this to gallons by dividing by 128 fluid ounces/gallon to get 450 gallons. Finally, divide by 15 gallons/drum to find that 30 drums are used.

Step-by-Step Solution

1
Calculate the total number of operational seconds in the 5-week period.
720000 seconds720{}000\text{ seconds}
Multiply 5 weeks by 5 days per week, 8 hours per day, and 3,600 seconds per hour: 5×5×8×3600=7200005 \times 5 \times 8 \times 3{}600 = 720{}000.
2
Calculate the total volume of lubricant used in fluid ounces.
57600 fluid ounces57{}600\text{ fluid ounces}
Multiply the rate of 0.08 fluid ounces per second0.08\text{ fluid ounces per second} by the total operational seconds: 720000×0.08=57600720{}000 \times 0.08 = 57{}600.
3
Convert the total fluid ounces to gallons.
450 gallons450\text{ gallons}
Divide the total fluid ounces by the conversion factor of 128 fluid ounces per gallon128\text{ fluid ounces per gallon}: 57600/128=45057{}600 / 128 = 450.
4
Calculate the total number of drums needed.
30 drums30\text{ drums}
Divide the total gallons by the capacity of a single drum (15 gallons15\text{ gallons}): 450/15=30450 / 15 = 30.

Key Concept

Multi-step dimensional analysis and unit conversion under compound rates
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