Apply the growth function:
A = P (1+ r) ^ t
Where:
p = original population : 200
r= growing rate (in decimal form) : 25/100= 0.25
t= hours
A = population after t hours
Replacing with the values given:
A = 200 (1 +0.25)^t
A = 200 (1.25)^ t
Graph:
To estimate the number of hours replace A by 2000
2000 > 200 (1.25)^t
2000/200 > 1.25^t
10 > 1.25^t
Log 10 > Log 1.25^t
Log 10 >t (Log 1.25)
Log 10 / log 1.25 > t
10.3 > t