Final answer:
To find the total cost of using a 750-watt electric iron for 4 weeks at 5 hours per week, with the cost of electricity at 5k per kWh, we calculate the energy consumed (15 kWh) and multiply it by the cost per kWh, resulting in a total cost of 0.75 currency units.
Step-by-step explanation:
To calculate the cost of electricity used by a 750-watt electric iron, we first need to convert that power usage into kilowatt-hours (kWh), which is the standard unit for measuring electrical energy consumed over time. Since a kilowatt is equal to 1,000 watts, we can find the usage per hour by dividing 750 watts by 1,000, yielding 0.75 kWh per hour.
The man uses the iron for 5 hours a week. Over 4 weeks, the iron is used for a total of 20 hours (5 hours/week x 4 weeks = 20 hours). To find the total kWh used over the 4 weeks, we multiply the hourly usage by the total number of hours used: 0.75 kWh/hour x 20 hours = 15 kWh.
With the cost of electricity at 5k (assuming this means 0.05 in currency units) per kWh, we can now find the total cost by multiplying the total kWh used by the cost per kWh: 15 kWh x 0.05 currency units/kWh = 0.75 currency units. Therefore, the cost of using the electric iron for pressing clothes over the period of 4 weeks is 0.75 currency units.