Carcass wrote:
The population of a bacteria culture doubles every 2 minutes. Approximately how many minutes will it take for the population to grow from 1,000 to 500,000 bacteria?
(A) 10
(B) 12
(C) 14
(D) 16
(E) 18
This is a case of geometric progression with a common ratio of 2 and first term being 1,000
a = 1,000
r = 2
The nth term is 5,00,000
The nth is calculated by using the formula a * (r^(n-1))
Accordingly n-1 will be 9 (for 5,12,000)
for the nth term there are n-1 iterations of doubling
and each iteration is of 2 mins
Accordingly 18 mins will be required
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