10. An aeroplane covers 200 mts in one sec. After covering
2/3
part of its journey, the
plane is slows down by 25% and it reaches its destination in the next 10 mins. What km
did the plane covered?
Answers
Answered by
2
Let the usual time taken by the aeroplane =x hr.
Distance =1500km
In first case-
speed= x1500 km/h ………..(1)
In second case-
time taken by aeroplane=x− 21
hr
∴ Speed= x− 21 1500 km/h ………(2)
Increased speed=250 km/h
So,
x− 1
1500 − x1500
=2501
1500 × 2x−1 − x1500
=250
2x−1
3000 − x1500
=250
(2x−1)x
3000x−3000x+1500
=250
2x 2
−x1500
=250
6=2x 2
−x2x 2
−x=6 2x 2
−x−6=02x 2
−4x+3x−6=0
2x(x−2)+3(x−2)=0
(x−2)(2x+3)=0
x=2,x= 2−3
So time can not be negative
x=2
then speed= x− 21
1500 = 2− 21
1500
=1000 km/h.
swapnabanerjee198920:
thank you so much
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