Question

An aeroplane goes from country a to b with an average speed of 450km/h and return with an average speed of 300 km/h. find the distance between the two countries if the flight take 15 hours in all.​

Answer 1

Let the time taken in the first part of the journey be t

So the time taken in next part of the journey is (15-t)

Now we all know, distance = speed × time

So, the distance remains same in both the cases.

According to the problem, we can make the equation,

$450t = (15 - t) \times 300$

Or,

$450t + 300t = 4500$

Or,

$t = 6$

So the time taken for the flight in the average speed of 450miles/hr is 6hrs.

So the distance covered was 450 × 6 = 2700 miles

Hence the distance between A and B is 2700 miles