the answer is A *but I am not sure*
The first thing you should know to solve this problem is the conversion of pounds to kilograms:
1lb = 0.45 Kg
We can solve this problem by a simple rule of three
1lb ---> 0.45Kg
125lb ---> x
Clearing x we have:
x = ((125) / (1)) * (0.45) = 56.25 Kg.
Answer
her mass expressed in kilograms is 56.25 Kg.
Total distance = 36500 m
The average velocity = 19.73 m/s
<h3>Further explanation</h3>
Given
vo=initial velocity=0(from rest)
a=acceleration= 1 m/s²
t₁ = 20 s
t₂ = 0.5 hr = 1800 s
t₃= 30 s
Required
Total distance
Solution
State 1 : acceleration


State 2 : constant speed

State 3 : deceleration


Total distance : state 1+ state 2+state 3

the average velocity = total distance : total time

Acceleration=9.81m/s^2
initial velocity=0m/s
time=.28s
We have to find final velocity.
The equation we use is
Final velocity=initial velocity+acceleration x time
Vf=0m/s+(9.81m/s^2)(.28s)
Vf=2.7468m/s
We would round this to:
Vf (final velocity)=2.7m/s