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A scientist is studying bacteria whose cell population [#permalink]
01 Jul 2008, 13:32
21% (02:46) correct
79% (01:49) wrong based on 67 sessions
A scientist is studying bacteria whose cell population doubles at constant intervals, at which times each cell in the population divides simultaneously. Four hours from now, immediately after the population doubles, the scientist will destroy the entire sample. How many cells will the population contain when the bacteria is destroyed?
(1) Since the population divided two hours ago, the population has quadrupled, increasing by 3,750 cells.
(2) The population will double to 40,000 cells with one hour remaining until the scientist destroys the sample.
given: population double every constant time interval. 1) population has quadrupled (double * double) in last two hours. => popuoation doubles every hr lets say original population was x then now it is x+3750 and 3x=3750 therefore current population = 3750*4/3 hence the current population is know at the time interval when it double is known=1hr therefore we can guess the population after 4hrs
2) if the population doubles 1 hr before the destruction then the constant time interval at which population increases is 3hr. so the next split would be after 6hrs.... but the destruction was to happen aftr 4hr??? there is a contradiction over here. and hence we should ignore point (2
Re: A scientist is studying bacteria whose cell population [#permalink]
19 Aug 2013, 17:20
A two hrs ago 1250 ....now 5000...as the ques says it doubles at constant time period.... if it has bcum 4 times in two hrs means it doubles every hour so aftr 4 hr 5000 *2^4+= 80,000- SUFFICIENT B only tells the number of cell after 3 hrs ....the rate at wich it doubles no info-insuffcient