A train left 30 minutes later than the Schedule time and to reach its destination in time it increased its speed by 250 km/hr. If the target is 1,500 km away, find the speed of the train?
বিকল্পসমূহ (নিজের উত্তর যাচাই করতে ক্লিক করুন):
সঠিক উত্তর
1 (750 km/hr)
বিস্তারিত ব্যাখ্যা ও বিশ্লেষণ:
Solution:
Let, the usual speed of plane be x km/hr
and the increased speed of the plane be y km/hr.
⇒ y = (x + 250) km/hr
Distance =1500 km [Given]
According to the question,
(Scheduled time) - (time taken at increased speed) = 30 minutes = 0.5 hours.
1500/x - 1500/y = 1/2
⇒ 1500/x - 1500/(x + 250) = 1/2 [∵ Time = Distance Speed]
⇒ (1500x + 375000 - 1500x)/x(x + 250) = 1/2
⇒ x(x + 250) = 750000
⇒ + 250x - 750000 = 0
⇒ + 1000x - 750x - 750000 = 0
⇒ x(x + 1000) - 750(x + 1000) = 0
⇒ (x - 750)(x + 1000) = 0
⇒ x = 750 or, x = - 1000
But speed cannot be negative.
∴ The usual speed is 750 km/hr.
