Subject: General Aptitude · Chapter: Time and Distance · Exam: 2005 · Marks: · Difficulty:
Aryan runs at a speed of 40 metres/minute. Rahul follows him after an interval of 5 minutes and runs at a speed of 50 metres/minute. Rahul's dog runs at a speed of 60 metres/minute and starts along with Rahul. The dog reaches Aryan and then comes back to Rahul, and continues to do so till Rahul reaches Aryan. What is the total distance covered by the dog?
(a)600 m
(b)750 m
(c)980 m
(d)1200 m
Answer
Answer (as printed): D
Explanation
Distance covered by Aryan in $5 \mathrm{min}=(40 \times 5) \mathrm{m}=200 \mathrm{m}$. Relative speed of Rahul w.r.t. Aryan $=(50-40) \mathrm{m} / \mathrm{min}$ $$=10 \mathrm{m} / \mathrm{min} .$$ Time taken to cover 200 m at relative speed$$=\left(\frac{200}{10}\right) \min =20 \min .$$ Distance covered by the dog in $20 \mathrm{min}=(60 \times 20) \mathrm{m}$ $$=1200 \mathrm{m} .$$