Question

an electric refrigerator rated 400W operates 8 hour what is the cost of energy to operate it
for 30days at rs 3.00per kw

Answer 1

$p = 400w \\ t = 8hr \\ energy \: consumed = 400 \times 8 \times 30 \\ = 96000 whr \\ 96kwhr \\ costof \: energy = 96 \times 3 \\ = 288rs$
hope you get it