Question

An electric lamp marked $60 \, W-220 \, V$ is used on an average $5$ hours a day in a month of $30$ days. Cost of electric power consumed at the rate of Rs. 2 per unit is

• A. Rs 30
• B. Rs 18
• C. Rs 9
• D. Rs 27

Answer 1

Answer: (B)

Rs 18

Answer 2

Electrical energy consumed by lamp in a month
$= 60 \times 5 \times 30 \, W \, h = 9000 \, W \, h = 9 \, k W \, h$
\hspace60mm = 9 units
$\therefore$ Cost of electrical power consumed $= Rs . 9 \times 2 = Rs. 18$