Answer:
Solving by the method of exponential growth.
bacteria = 2
after one hr = 2² = 4
after 2nd hr = 2³ = 8
after 3rd hr = 2⁴ = 16
after 4th hr = 2⁵ = 32
How about putting one battery in the freezer while putting another by a radiator or something that gives off heat. Leave them for an hour, then place them in an object that uses batteries and time how long it takes for it to die: Note: It may take many hours for the battery to fully deplete.