Questions :
A person travels from city P to city Q. If he travels at a speed of 60 km/h, he arrives 1 hour early. If he travels at a speed of 40 km/h, he arrives 1 hour late. What is the distance (in km) between city P and city Q ?
Options :
- 240 km
- 200 km
- 220 km
- 180 km
correct answer : a)
Explanation :
Let the distance between city P and city Q be d km. Since one journey results in arriving 1 hour early and the other results in arriving 1 hour late, the difference in travel times is 2 hours. Therefore,
d/40 − d/60 = 2
Taking LCM 120,
(3d − 2d)/120 = 2
d/120 = 2
d = 240 km
Hence, the distance between city P and city Q is 240 km. Option (b) 200 km, option (c) 220 km, and option (d) 180 km do not satisfy the given conditions and are therefore incorrect.