a culture of bacteria grows at a rate which is inversely propertional to the square root of the number present. if there are 9 units present initially and 16 unit after 2 days. find in how many days the bacteria will be 36 units?

Question

hartnn · Answer

so, $\large a_n=\dfrac{k}{\sqrt{a_{n-1}}}$
with a1 = 9

got this equation ?

hartnn · Answer

with a2 = 16, n=2
you could get the value of k

shrutipande9 · Answer

haann...yes ok

shrutipande9 · Answer

ok cool...got it..thnx!:D

hartnn · Answer

welcome ^_^

shrutipande9 · Answer

i got n as 10.21 days....is it correct?

hartnn · Answer

what u got k as ?

shrutipande9 · Answer

fir se ainvyi medal huh

shrutipande9 · Answer

i got k as 12.33

hartnn · Answer

a2 = 16 = k/ sqrt 9
didn't u use this ?

shrutipande9 · Answer

see...i also need 2 find d constant c...

shrutipande9 · Answer

see wat i was doing...i took dN/dt=k/sqr rt N
here N is ur a

hartnn · Answer

ok

shrutipande9 · Answer

so i need 2 integrate dis thing rite

hartnn · Answer

right, calculus stuff....
should have known

shrutipande9 · Answer

so i m in d rite direction na?

hartnn · Answer

yes, go on

shrutipande9 · Answer

so then after integrating and subs t=0 and N=9 i got c=18

hartnn · Answer

yup,

shrutipande9 · Answer

ok cool..so in d same manner N=16 t=2 so k=12.33
and den i reached t=10.21days

hartnn · Answer

yes, i too get 10,219

shrutipande9 · Answer

one more thing int of....sqr rt dN/dt=2(sqr rtN)^3/3 RITE?

hartnn · Answer

yes, because we divide by the power, which is here 3/2

shrutipande9 · Answer

COOL.....thnx

hartnn · Answer

welcome ^_^

shrutipande9 · Answer

btw aj ye mera saval tha..not my sister's:P

hartnn · Answer

cool! but m equally happy to help you both :)

shrutipande9 · Answer

:) maths guru

hartnn · Answer

guru bhai guru bhai avya che..dhoom dhadaka karela che :P

shrutipande9 · Answer

guru bhai ekdum maja ma che:)