IIT JEE , AIEEE Forum - Mathematics , Differential Calculus - all aspirants of jee must answer this question

vivek54761

Q-1)A population of bacteria tends to double every four hours. If there are 5000
bacteria at 9:00 a.m., then how many will there be at noon?

q-2)Five gramsof a certain radioactive isotope decay to three gramsin 100
years. After how many more years will there be just one gram?

waterdemon

The answer of first one I suppose is "7500"

And the answer of "after another 100 years"

Although it is not possibly.

plZ rate me if I am correct.
Cheers !!!!!!!!!!!!!!!!!!!@@!!!!!!!!!!!!!!!!

vivek54761

ur absolutely wrong

vivek54761

waterdemon ask any professor or call him to get urgent answer i bet u he know nothin.

waterdemon

if that is not the answer then I think no one knows the answer
But except for u.

Good question

Do nudge me when u tell the answer.
Cheers !!!!!!!!!!!!!!!!!!!!!!!!!!

him26.89

2) it follows first order kinetics.

N_T=N_o e^-kt

=> 3 = 5 e^(-100k)

ln3/5 = -100k

as per qun

1 = 5 e^(-kt)

ln1/5 = -kt

on dividing both

100/t = 1 - (ln3)/ln5

=> t = 315

hence it req. 215 more years.

him26.89

1) i think it's 8409.

using

N_t = N_oe^kt

k = (1/4)ln2

now,

N_t = 5000e^3k

on subst. we get 8409.

vivek54761

very good him congrats ur right

vivek54761

u have a very good concept
i think u will make it to iit
keep going
tell me ur email id and i will send u ebooks of such good questions
all americans refer this books

puneet

hey

I think no interference is required here .

cheers

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