JEE Main202124 Feb 2021Morning ShiftMathematicsDifferential EquationsActual
The population P = P t at time t of a certain species follows the differential equation d P d t = 0 . 5 P - 450 . If P 0 = 850 , then the time at which population becomes zero is:
Options
- Alog e 9
- B2 log e 18
- Clog e 18
- D1 2 log e 18
Correct answer
B. 2 log e 18
Step-by-step solution
d P d t = 0 . 5 P - 450 ⇒    ∫ 0 t d p P - 900 = ∫ 0 t d t 2 ⇒    In P t - 900 0 t = t 2 0 t ⇒    In P t - 900 - In P 0 - 900 = t 2 ⇒    In P t - 900 - In 50 = t 2 for P t = 0 ⇒   In 900 50 = t 2 ⇒ t = 2 In 18