Math, asked by Tg98, 1 year ago

A plane left 30 minutes later than its schedule time and in order to reach its destination 1500km away in time it had to increase its speed by 100 km

Answers

Answered by nikitasingh79
32
Incomplete Question : we have to find the usual speed of an aeroplane.
SOLUTION:
Let x km/h be the usual speed of an aeroplane .
Total Distance to reach the destination = 1500 km
ATQ..
Case 1.
Time = Distance /speed = (1500 / x) h

Case 2.
Let( x +100 )km/h be the new speed of an aeroplane

Time = Distance / Speed = 1500 / (x +100) Hrs

= [1500 / x] - [1500 / x+100] = 30 min
= [1500 / x] - [1500 / x+100] = 30/60
[ 1 min = 1/60 h]
=[1500 / x] - [1500 / x+100] = 1/2 h
= 1500 [ 1/x - 1 /(x+100)] = ½
=1500 × 2 [ x +100 - x / (x(x+100)] = 1
=3000 [ 100/(x²+100x) ]= 1
300000= x² +100x
x² +100x -300000= 0
x² +600x -500x -300000= 0
x(x + 600) - 500(x +600)= 0
(x +600 )(x -500) = 0
x = -600 or x= 500
Since, the speed can not be negative.
Hence, the usual speed of an aeroplane = 500 km/h.

HOPE THIS WILL HELP YOU..
Answered by topanswers
5

Given:

Late = 30 min

Distance = 1500 km

Speed increase = 100 km / hr

To find:

The usual speed.

Solution:

By formula,

Speed = Distance / Time  

Since the time is unknown,  

Consider x for time,

Speed original = 1500 / x  

Time taken = ( x - 1 / 2 )  

Therefore,

Substituting the value of x,

Speed new = 1500 / (x - 1/2)  

Speed New - Speed original = 100

( 1500 / ( x - 1 / 2 ) ) - ( 1500 / x ) = 100

150 ( ( 10 / x - 1 / 2 ) - 10 / x = 100  

30 x -30 x +15 = 2x^2 - x

15 = 2x^2 - x

2x^2 - x -15 = 0

Solving,

x = -5/2

x = 3

As time cannot be negative,

The usual time taken by the plane is 3 hr

Speed original = ( 1500 / 3 ) = 500 km / hr

Hence, the usual speed of the plane is 500 km / hr

Read more on Brainly.in - https://brainly.in/question/3087358

Similar questions