Question

A household uses the following electric appliance:
1) Refrigerator of rating $400W$ for $10$ hours daily
2) $2$ Electric Fans of rating $80W$ each for $12$ hours daily
3) $6$ electric tubes of rating $18W$ each for $6$ hours daily
Calculate the electricity bill of the household for the month of June if the cost per unit electric energy is Rs $3.00$.

Answer 1

Hint: -Convert the rating of each appliance into SI units and then multiply it by the number of hours the particular appliance is run daily. This gives the units consumed by the appliance in one day. If there are more than 1 appliance of the same kind, multiply it accordingly. Add all such values of all the appliances. This will give the total units consumed in one day. Now, the months of June consist of $30$ days. So, multiply the units consumed in a day by 30 to get units consumed in June. Multiply this answer by the rate of each unit of electric energy as given in the question to find out the electricity bill for June.

Step-by-step solution:
First, convert the rating of each appliance into the SI unit that is $KW$.
We know that, $1W = {10^{ - 3}}KW$
Rating for refrigerator = $400W = 400 \times {10^{ - 3}} = 0.4KW$
Rating for each fan = $80W = 80 \times {10^{ - 3}} = 0.08KW$
Rating for each electric tube = $18W = 18 \times {10^{ - 3}} = 0.018KW$
Now, multiply each rating with the number of hours they are used every day.
We get,
For refrigerator, $0.4 \times 10KWh$
For each fan, $0.08 \times 12KWh$
For each electric tube, $0.018 \times 6KWh$
Now, multiply these values with the number of that kind of appliances respectively, we get,
For refrigerator, $0.4 \times 10 \times 1 = 4KWh$
For fan, $0.08 \times 12 \times 2 = 19.2KWh$
For the electric tube, $0.018 \times 6 \times 6 = 0.648KWh$
Add these values to get units consumed in a day.
We get, $(4 + 19.2 + 0.648)KWh$ = $23.848KWh$
Since June has $30$ days, multiply this by $30$ to get the number of units consumed in June
⇒ $23.848KWh$ × $30$ = $715.44units$
Since the rate of each unit is $Rs.3.00$, we multiply the above value by $3.00$ to get the final answer.
$715.44 \times 3$ = $Rs.2146.32$

Note: Convert into SI units before starting the question. Don’t forget to multiply by the number of appliances otherwise, it will be the value of only a single appliance. And it is important to know that June has 30 days, so students should not be confused in that part.