Latest TCS Aptitude Question SOLUTION: The number of bacteria in a colony was growing exponentially. At 4 pm yesterday the number of bacteria was 400 and at 6pm yesterday it was 3600. Howmany bacteria were there in the

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The number of bacteria in a colony was growing exponentially. At 4 pm yesterday the number of bacteria was 400 and at 6pm yesterday it was 3600. Howmany bacteria were there in the colony at 7 pm yesterday?
a.3600
b.10800
c.32400
d.14400

Asked In TCS Rimu Mukherjee (12 years ago)

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Nirmal  (12 years ago)

growing exponentially.so at 4p.m.it is 400...and at 5 p.m it is 400*3=1200,and at 6p.m it is 1200*3=3600, and at 7p.m.it shuld be 3600*3=10800

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MANOJ T M  (12 years ago)

at 4pm ,no. of bacteria =400
and it is incresed exponentialy...
at 6pm,no. of bacteria=3600
3600/400 = 9 = 3^2,for 2 hours
at 7pm,which means 3 hours later,
no. of bacteria = 400 X 3^3 = 400 X 27 = 10800
which is option B

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saurabh gupta  (12 years ago)

At 4 pm no. of bacteria=400
and it increased exponentially
them after 1 hour(at 5pm) increased bacteria = (400*4)/2=800
and total bacteria after 1 hour = 800+400 = 1200
and again after 1 hour (at 6pm) increased bacteria = (1200*4)/2=2400
and total bacteria = 2400 + 1200= 3600 (as given in question)
then at 7 pm(after 1 hour again) increased bacteria is= ( 3600*4)/2= 7200
and total bacteria at 7pm is= 7200 + 3600 =10800
and answer B is correct

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satyajit kumar singh  (12 years ago)

here at 4pm no of bacteria is 400, after 2 hours at 6pm it is 3600. since in 1 hour at 5pm it is 3 times i.e,400*3=1200 and in next 1 hour at 6pm it is again 3 times i.e,1200*3= 3600, then at 7pm it will be 3600*3=10800
So the answer is b. 10800

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anwesha  (12 years ago)

given dat 3600=400 exp(rate*time)....time is 2 hrs...find rate by using log....
then the ans cn b solved using the same equation...u kno d rate and time=3 hr....ans is 10800

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Arun kumar  (12 years ago)

Answer is 14400.
At 4 pm no of bacteria = 400.
At 6 pm no of bacteria = 3600. (9 * 400 )(It increases at rate of 9 per 2 hours)
At 8 pm no of bacteria = 32400.(9 * 3600)
At 4 pm no of bacteria = 14400.
(7pm)=(8pm-6pm)/2
=>(32400-3600)/2
=> 28800/2
=14400.

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