Book Online Demo

Check Your IQ

Try Test

Courses

Offline Centres

In a flight of 2800 Km, an aircraft was slowed down due to bad weather. Its average speed for the trip was reduced by 100 km/hr. and time increased by 30 min. Find the original duration of the flight.

see full answer

Talk to JEE/NEET 2025 Toppers - Learn What Actually Works!

Real Strategies. Real People. Real Success Stories - Just 1 call away

An Intiative by Sri Chaitanya

3 \frac{1}{2} hours

4 \frac{1}{2} hours

5 \frac{1}{2} hours

2 \frac{1}{2} hours

answer is A.

(Unlock A.I Detailed Solution for FREE)

Ready to Test Your Skills?

Check your Performance Today with our Free Mock Test used by Toppers!

Take Free Test

Detailed Solution

Suppose, original speed =x km/hr.
Now, time of flight

= \frac{2800}{x} hours

New speed

= (x - 100) km / hr

Time of flight for new speed

= \frac{2800}{x - 100} hours

Now, time increased by 30 min. Thus,

\frac{2800}{(x - 100)} - \frac{2800}{x} = \frac{30}{60}

\frac{1}{2} = \frac{2800 x - 2800 (x - 100)}{x (x - 100)}

x^{2} - 100 x - 560000 = 0

x^{2} - 800 x + 700 x - 560000 = 0

x (x - 800) + 700 (x - 800) = 0

(x - 800) (x + 700) = 0

x - 800 = 0 x + 700 = 0

x = 800, - 700

Neglect negative value.
Thus, original speed x= 800 km/hr.
Time of flight for original speed

T = \frac{2800}{800}

T = 3 \frac{1}{2} hours

.
Correct option is 1

Watch 3-min video & get full concept clarity

JEE

NEET

Foundation JEE

Foundation NEET

CBSE