Discussion
A plane travelled a certain distance at a uniform speed. Had the speed been 216 kmph more, the journey would have taken one hour less and had the speed been 108 kmph less, the journey would have taken one hour more. Find the distance travelled by the plane.
Answer: D
The distance is 1296 km.
Let the speed be \(v\) and the distance \(d\). The two conditions give
\[ \begin{aligned} \frac{d}{v} - \frac{d}{v + 216} &= 1 \Rightarrow 216d = v(v + 216) \\ \frac{d}{v - 108} - \frac{d}{v} &= 1 \Rightarrow 108d = v(v - 108) \end{aligned} \]
Dividing, \(2 = \frac{v + 216}{v - 108}\), so \(v = 432\) km/h. Then \(d = \frac{432 \times 648}{216} = 1296\) km, a 3-hour flight. Check: at 648 km/h it takes 2 hours, at 324 km/h 4 hours.
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development