Bactria double every 3 mins It is N in 1 hour when was it N 4

N in 1hr
N/2 in 57mins
N/4 in 54mins
11 years agoHelpfull: Yes(6) No(1)
let initially no. of bacteria is 1
after 1 minute 3
after 2 minutes 9
....
it would be gp
N=60
N/4=15
this gp contains 16
where a=1,r=3,n=16
N/4=a(r^n-1)/(r-1)
1(3^16-1)/(3-1)=>21523360
11 years agoHelpfull: Yes(1) No(13)
let at first there is x no. of bacteria.
after 3 mins=2x
after 6 min=(2^2)x
after 9 min=(2^3)x
...after 60min=(2^19)x=N
so,N/4=(2^17)x
11 years agoHelpfull: Yes(0) No(8)
N=60mint
60/4=15
11 years agoHelpfull: Yes(0) No(7)
N=1hr i.e 60 min
N/4-> x
=>x=[(N/4)*60]/N
x=15 min..thus at 15th min,it was N/4
10 years agoHelpfull: Yes(0) No(3)
N in 1 hr means N/2 in 30 min N/4 in 15 mins so ans is 15 mins.
10 years agoHelpfull: Yes(0) No(4)
if N=1hr i.e 60 min
60min----N [ 2(N/2)=N ]
57 min----n/2(because every 3 min it doubles) [ 2(N/4)=N/2 ]
54 min-----N/4 So 54 mins is answer
10 years agoHelpfull: Yes(0) No(0)

Bactria double every 3 mins. It is N in 1 hour, when was it N/4?