For this case we have an equation of the form:

Where,
A: initial amount
b: growth rate
t: time in years.
Substituting values we have:

By the time the population is triple we have:

Rewriting we have:

Clearing t we have:
Answer:
It will take for the population to triple about:
t = 73 years
Answer:
Remember The distance, speed, time triangle
Step-by-step explanation:
Formula is
Speed x time=distance
Distance divided by speed=time
distance divided by time=speed
HIGH SPEED= 40*30=1200 cm
low speed= 25*51=1275 cm
total= 1200+1275=2475 cm