Let's V the speed of the girl in step
v the speed of the escalator in step
L the length between ground and floor.
V*60+v*60=L ==> V+v=L/60
V*90-v*90=L ==> V-v=L/90
2V=L(3+2)/180
==>V=5L/360
Time to climb (in step) with v=0 (escalator standing still)
V*t=L==> t=L/V=L/(L*5/360)=72
The girl will count 72 steps.
Answer:
growth
Step-by-step explanation:
We have to use the function A(t)= a(1 +/- r)^t
So A is going to be the answer- the area after 8 years. t is going to be 8, because t is time. a is 2400 because that's the starting value. Finally, we're going to turn 5.75% into it's decimal form of .0575. That's going to be r, and because the area is decreasing, we will subtract r from 1.
Our new function is:
A=2400(1-.0575)^8
Simplify a little bit.
A=2400(.9425)^8
Bring .9425 to to power of 8 and then multiply by 2400 because PEDMAS.
A=1494.38366866
The rounded answer is 1494 kilometers squared.
