Q. If natality is represented by $–B$ If mortality is represented by $–D$ If immigration is represented by $–I$ If emigration is represented by $–E$ If population density is represented by $–N$ Then population density at time t+1 is represented by
A) $N_{t + 1} = N_{t} - \left\lbrack (B + I) \right\rbrack - \lbrack(D + E)\rbrack$
B) $N_{t + 1} = N_{t} + \left\lbrack (B + I) \right\rbrack - \lbrack(D + E)\rbrack$
C) $N_{t + 1} = N_{t} + \left\lbrack (B + I) \right\rbrack + \lbrack(D + E)\rbrack$
D) $N_{t + 1} = N_{t} - \left\lbrack (B + I) \right\rbrack + \lbrack(D + E)\rbrack$
Explanation
‘N’ is the population density of time $t$ then its density at time $t\ + 1$ is $Nt + 1 = Nt + \lbrack(B\ + \ I) - (D\ + \ E)\rbrack$ We can see from the above equation that population density increases if the number of birth plus number of immigrants ($B + I)$ is more than the number of death plus the number of emigrants ($D\ + E$)
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.