Answer:
3 hours
Step-by-step explanation:
Distance between South Central High and Redding = 480km
Distance= Average Speed X Time
Let the speed of the express train=x
Let the time taken BG the train=t
For the train:
480=xt...(1)
Since the plane flies 40km/hr faster
Speed of the Plane=x+40
They can save one hour using the plane, so Time taken by the plane
=(t-1)hours
For the plane:
Distance= Average Speed X Time
480=(x+40)(t-1)....(2)
Equate equations 1 and 2 since the distances are equal.
xt=(x+40)(t-1)
xt=xt-x+40t-40
x=40t-40
Substitute x=40t-40 into equation (1)
480=xt
480=(40t-40)t
40t²-40t-480=0
Dividing all through by 40
t²-t-12=0
t²-4t+3t-12=0
t(t-4)+3(t-4)=0
(t-4)(t+3)=0
t-4=0 or t+3=0
t= 4hours (Since t cannot be negative)
Since it will take (t-1) hours to fly, it takes 3 hours to fly to Redding.
Step-by-step explanation:
Below is an attachment containing the solution.
