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/hr and the time of flight increased by $30$ minutes. The duration of the flight is :

• A. $1$ hour
• B. $2$ hour
• C. $3$ hour
• D. $4$ hour

Answer 1

The correct option is A $1$ hour

Let duration of the flight was $X$ hours.
Increased time $=30$ minutes $=\frac{1}{2}$ hour
Now,
$X\times (2X+1)=3$
$2X^2+X=3$
$2X^2+X-3=0$
$(2x+3)(X-1)=0$
On solving, we get,
$X=-3,1$
$X$ is the time so it can not be negative
$X=1$ hour.