Question

a plane left 30 minutes later than the scheduled time and in order to reach its destination 1500 km away in time it has to increase its speed by 100 kilometre per hour from its usual speed find its usual speed​

Answer 1

Answer:

Answer:

Its usual speed is 500 km /hr.

Step-by-step explanation:

Let the original speed be x

Distance = 1500 km

Original time = \frac{Distance}{Speed}

Speed

Distance

Original time = \frac{1500}{x}

x

1500

It had to increase its speed by 100 km /hr

New speed = x+100

New time = \frac{Distance}{Speed}

Speed

Distance

=\frac{1500}{100+x}

100+x

1500

Since we are given that plane left 30 minutes late

So, \frac{1500}{100+x}-\frac{1500}{x}=\frac{1}{2}

100+x

1500

−

x

1500

=

2

1

\frac{1500}{100+x}-\frac{1500}{x}=\frac{1}{2}

100+x

1500

−

x

1500

=

2

1

(x-500)(x+600)=0(x−500)(x+600)=0

x=500, - 600x=500,−600

Since speed cannot be negative

So, its usual speed is 500 km/hr