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OK, here we are trying to compare two air conditioners
both of which are going to last 10 years.
One consumes less power and the other one high power.
They both operate for 2,400 hours annually.
So we have the power.
And we have the time of usage data.
So we need to calculate how much energy each
of these will consume.
So life of one, our first air conditioner, is 10 years.
And second one is 10 years.
Power is 775 least efficient one watts.
And the other one is 700 watts.
We have the time of usage.
Time of usage is given as 2,400 hours.
And this one is also 2,400 hours.
So the energy consumed is given by power multiplied by
time of usage.
So in this case it would be 775 watts
multiplied by 2,400 hours.
And that will be 1,860,000 watt hours.
And for this air conditioner it would be 700 watts times
2,400 hours.
That will be 1,680,000 watt hours.
So we need to convert this into kilowatt hours.
Because we buy by kilowatt hours.
So dividing it by 1,000 and dividing here by 1,000, we get
kilowatt hours.
So this air conditioner will consume 1,860
kilowatt hours per year.
This one would consume 1,680 kilowatt hours per year.
So in 10 years, the energy consumption is
18,600 kilowatt hours.
This is simply multiplying yearly
consumption by 10 years.
And now for the least efficient one, it would be
1,680 multiplied by 10.
That would be 16,800 kilowatt hours.
We know the price of each of these, each of
the kilowatt hours.
That is it is sold at the rate of $0.8 per kilowatt hour.
So when you multiply that by 0.8, both sides, the cost to
operate this one would be $1,488.
And this one would be $1,344.
So difference is $144, which means the least efficient one
basically costs $144 more.
And the best one would be, actually, even if it is priced
$144 more, it would work out to be the same amount in the
long run over 10 years.
But we will be helping the environment by not burning the
difference between these two kilowatt hours.
A couple thousand kilowatt hours over 10 years, that
would be the help for the environment.