1.There are 3 amoebae in a jar.They double every minute.The jar is completely filled with amoebae in 20 minutes.The jar is half full in _______

Asked by  | 16th Mar, 2013, 10:18: AM

Expert Answer:

Since, the amoebae double every minute,
after 1 minute, we would have 3*2,
after 2 minutes, there would be 3*2^2
after 3 minutes, there would be 3*2^3
So, after n minutes, there would be 3*2^n. 
The jar is full in 20 minutes, i.e, there would be 3*2^20 amoebae in the jar. 
So, the half full jar would represent 3*2^20/2 amoebae i..e 3*2^19. 
Comparing, we will get that the jar would be half full in 19 minutes. 

Answered by  | 16th Mar, 2013, 07:42: PM

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