SOLUTION: Aeroplane left 30 minutes later than its scheduled time and in order to reach distination 1500 KM away in time,it has to increase its speed by 250 km/h from its usual speed.determ

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Question 914830: Aeroplane left 30 minutes later than its scheduled time and in order to reach distination 1500 KM away in time,it has to increase its speed by 250 km/h from its usual speed.determine it usual speed
Found 2 solutions by josgarithmetic, lwsshak3:
Answer by josgarithmetic(39621) (Show Source):
You can put this solution on YOUR website!
r, the usual speed

______________speed_______time_______distance
REGULAR________r__________(___)_______1500
LATE__________r+250_______t-1/2_______1500

The uniform rates rule for travel will allow an expression for the missing time for the regular trip.

______________speed_______time_______distance
REGULAR________r__________(1500/r)_______1500
LATE__________r+250_______t-1/2_______1500

This means that the tabulated number information can be also shown as:

______________speed_______time_______distance
REGULAR________r__________(1500/r)_______1500
LATE__________r+250_______1500/r-1/2_______1500

Again using the basic rule for traveling uniform rates, we can form an equation for the LATE trip. ; which is an equation in just the single variable, r, which is also what the question asks to find. Solve the equation for r.

Answer by lwsshak3(11628) (Show Source):
You can put this solution on YOUR website!
Aeroplane left 30 minutes later than its scheduled time and in order to reach distination 1500 KM away in time,it has to increase its speed by 250 km/h from its usual speed.determine it usual speed
***
let x=usual speed of plane
x+250=increased speed of plane
30 min=1/2 hr
travel time=distance/speed
...

lcd:x(x+250)
1500(x+250)-1500x=x(x+250)/2
1500x+375000-1500x=x^2+250x/2
750000=x^2+250x
x^2+250x-750000=0
(x+1000)(x-750)=0
x=750
usual speed of plane=750 km/hr