Subject: General Aptitude · Chapter: Time and Distance · Exam: 2003 · Marks: · Difficulty:
Robert is travelling on his cycle and has calculated to reach point A at 2 P.M. if he travels at 10 kmph; he will reach there at 12 noon if he travels at 15 kmph. At what speed must he travel to reach A at 1 P.M.?
(a)8 kmph
(b)11 kmph
(c)12 kmph
(d)14 kmph
Answer
Answer (as printed): C
Explanation
Let the distance travelled be $x \mathrm{km}$.Then, $\frac{x}{10}-\frac{x}{15}=2 \Leftrightarrow 3 x-2 x=60 \Leftrightarrow x=60 \mathrm{km}$. Time taken to travel 60 km at $10 \mathrm{km} / \mathrm{hr}=\left(\frac{60}{10}\right) \mathrm{hrs}=6 \mathrm{hrs}$. So, Robert started 6 hours before 2 P.M. i.e., at 8 A.M. $$\text { ∴ } \text { Required speed }=\left(\frac{60}{5}\right) \mathrm{kmph}=12 \mathrm{kmph} .$$