Question

A plane left 30 minutes late than the scheduled time and in order to reach the destination 1500km away intime, ithad to increase the speed by 250km/hr from the normalspeed. Find its usual speedA plane left 30 minutes late than the scheduled time and in order to reach the destination 1500km away intime, ithad to increase the speed by 250km/hr from the normalspeed. Find its usual speed

Answer 1

hope this helps you....

Answer 2

Solution :-

Let the original speed of train be x km/hr
New speed = (x + 250) km/hr

We know that,
Time = Distance / Speed

Given : A plane left 30 minutes or 1/2 hours later than the scheduled time.

According to the question,

=> 1500/x - 1500/(x + 250) = 1/2
=> (1500x + 37500 - 1500x)/x(x + 250) = 1/2
=> 2(37500) = x(x + 250)
=> 75000 = x² + 250x
=> x² + 250x - 75000 = 0
=> x² + 1000x - 750x - 75000 = 0
=> x(x + 1000) - 750(x + 1000) = 0
=> (x - 750) (x + 1000) = 0
=> x = 750 or x = - 1000

∴ x ≠ - 1000 (Because speed can't be negative)


Hence,
Its usual speed = 750 km/hr