Question

In a house 5 bulbs, rated as 220 V-100 W are used 8 hours daily. Find the expenditure for 30 days at the rate of 2 per unit.​

Answer 1

$\LARGE{\bf{\underline{\underline{GIVEN:-}}}}$

• There are 5 bulbs.
• The voltage (v) = 220V.
• Power (P) = 100 W.
• They are used for 8 hours daily.

$\LARGE{\bf{\underline{\underline{TO:FIND:-}}}}$

• We need to find the expenditure if they are used for 30 days.
• The rate is 2 Rs. per unit.

$\LARGE{\bf{\underline{\underline{SOLUTION:-}}}}$

▣ Let's calculate the power of one bulb in kWh:

$\sf Energy(E)=\dfrac{Power \times time}{1000}$

We divide the value by 1000 so that the unit is in kWh.

$\sf E=\dfrac{100 \times 8 \times 30}{1000}$

$\sf E=24 kWh.$

Energy of 5 bulbs would be 24×5⇒120kWh.

The rate is 2 Rs. per unit. Therefore:

Cost=Energy×rate.

Cost=120×2

Cost=240 Rs.

∴THE COST IS 240 Rs.