Question

a man uses a 900 watt electric iron to press his clothes for an average of 4 hours a week for five weeks if the cost of an electric energy is 3 Kobo per unit calculate the cost of electric energy for pressing​

Answer 1

`\boxed{\sf54 \: kobo}`

Step-by-step explanation:

Energy = Power × Time

Energy = 900× 4 ×5 = 18000 wh

Energy = 18000 wh = 18 kwh

Cost of 1 unit electricity = 3 kobo

cost of 18 unit electricity= 18 × 3 = 54 kobo

Answer 2

54 Kobo

Step-by-step explanation:

Units of electricity are measured in kilowatt hours (kWh).

Given information:

• 900 watt electric iron
• Appliance usage = 4 hours a week for 5 weeks
• Unit cost of electricity = 3 Kobo per kWh

Step 1

Convert the wattage of the electric iron from watts to kilowatts.

1000 watts (W) = 1 kilowatt (kW)

⇒ 900 watts = 1 ÷ 1000 = 0.9 kilowatts

This means that the power consumption of the electric iron is 0.9 kW per hour of use.

Step 2

Total hours spent pressing clothes:

= 4 hours per week for 5 weeks

= 4 × 5

= 20 hours

Total power consumption:

= number of kW × number of hours

= 0.9 × 20

= 18 kWh

Step 3

To find the total cost, multiply the total kWh by the cost per kWh:

⇒ Cost = 18 × 3 = 54 Kobo