The manager of a bank recorded the amount of time each customer spent waiting in line during peak business hours one Monday. The waiting times are shown below. 2
3
7
21
19
8
S
12
6
5
7
2
Find the mean waiting time. Round your answer to one decimal place.
8.0 min
7.2 min
7.5 min
6.8 min

I'm assuming that you want to know how many hours until they are the same temperature. Here is the equation you can use to figure it out:

40 + 5h= 340-45h

Here is how I would solve it:

40+ 5h= 340 - 45h
  +45 h          + 45 h

40+50h= 340

-40          -40

50h= 300
 /50   /50

h= 6

It will take 6 hours for the two appliances to reach the same temperature, assuming the power doesn't go out. For reference, they would be at 80 degrees.