# A bacterial cell dividing every minute fills up a cup in 60 minutes. What time would it take to fill half the cup?

A bacterial cell divides in one minute. So, half cup of bacteria will divide all at a time and double their numbers to fill the cup in only another one minute. If it takes 60 minutes by the bacteria to fill the entire cup, half cup must have been filled in one minute less than 60 minutes which is 59 minutes. After that in one minute another half of the cup will get filled.

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30 min...

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hmmm right arshi.... 59 minutes is the answer but i want to know how to solve such questions...???

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it is given ih the book that under favourable conditions, many bacteria undergo binary fission after every 20-30 minutes . A binary fission after  every 20 minutes will produce 4.7 x 1021 descendants with a weight of 2000 tonnes in just 24 hours.

but with the help of this information given in the book how can we calculate the number of bacteria produced in binary fission in the given intervel of time.

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actually the info. that's given has no relation with the answer...........
Its just that in 60 minutes, the full cup is filled , It is a known fact that when a bacteria divides by binary fission.... it doubles itself in number. So after the cup is half full, only 1 more binary fission is required is required to fill the whole cup, as if each bacteria in the half filled cup is gonna undergo binary fission and double itself , then the whole cup would  become full. Since 1 binary fission takes place in 1 minute.....we have to subtract 1 minute from the total time, i.e.60 - 1 = 59 minutes.
hope u understood wat i was tryin to convey!!!

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