Heater

Algebra Level 3

You sleep 7 hrs daily in heated room.

You have a electric heater with 2 modes which is Super and Auto.

If heater is on for 1 hour then it consumes 2 units of power.

You observe that during sleep super mode could heat room in just 2.5 hrs for whole night.

While auto mode requires heater to run whole night during which it starts heat for 60 minutes and then take break for 30 minutes.

Rate of power is 0.75$ per unit.

Choose best option and say what is electricity expense due to heater for December month.

132.75 109.50 116.25 125.00

2 solutions

Josh Speckman
Jul 15, 2014

Cheating: Note that $116.25$ is the only answer choice divisible by (31), and December has $31$ days. Thus, logically, the answer is $116.25$

Aaditya Bhatt
Jul 11, 2014

As it said you require 7 hrs of sleep every day.

Now if heater is in Super mode than it will consume 2.5 hrs x 2 units = 5 units a day.

While in auto mode it will run for 300 minutes i.e. 5 hrs as follows.

60 minutes ON + 30 minutes OFF + 60 minutes ON + 30 minutes OFF and so on...

So in auto mode daily 5 x 2 = 10 units will be consumed.

Hence best option is Super mode.

In December month total units consumed will be 31 days x 5 units = 155 units x 0.75$ = 116.25$.

7 hours of sleep.... that is 420 minutes I guess?

Vaibhav Mishra - 6 years, 11 months ago

yes buddy.... changed it...

Aaditya Bhatt - 6 years, 10 months ago