Question

In a flight of 600 km, an aircraft was slowed down due to bad weather. Its average speed for the trip was reduced by 200 km/h and the time of flight increased by 30 min. The duration of the flight is

Options

• 1 h
  

• 2 h

• 3 h

• 4 h

Answer 1

1 h
Explanation:
Let the duration of the flight be x h.

Then, `600/x-600/(x+1/2)=200`

⇒ `600/x-1200/(2x+1)=200`

⇒ `3/x-6/(2x+1)=1`

⇒ `3(2x+1)-6x=x(2x+1)`

⇒ `x(2x+1)=3`

⇒ `2x^2+x-3=0`

⇒ `(2x+3)(x-1)=0`

∴ x = 1 h  ...[leaving the -ve value of x]