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Every day a family uses: a fan of 60 W for 10 hours, a tube light of 36 W for 6 hours, a television…

Try it on paper first. A hint, the key idea and the worked solution are here when you need them.

Every day a family uses:

a fan of $60\ \text{W}$ for $10$ hours,
a tube light of $36\ \text{W}$ for $6$ hours,
a television of $80\ \text{W}$ for $4$ hours,
a refrigerator that works the same as $180\ \text{W}$ for $8$ hours.

Find the units used in $30$ days, and the bill at $6.5$ rupees a unit.

Need a reminder? The key ideaShow

Energy $E = Pt$ . One unit is $1\ \text{kWh} = 3.6 \times 10^{6}\ \text{J}$ : units $=$ power in kW $\times$ time in hours. Cost $=$ units $\times$ price of one unit.

The worked solution

Have you tried it?

Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.

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