Subject: General Aptitude · Chapter: Time and Distance · Exam: 2010 · Marks: · Difficulty:
Ravi can walk a certain distance in 40 days when he rests 9 hours a day. How long will he take to walk twice the distance, twice as fast and rest twice as long each day?
(a)40 days
(b)50 days
(c)80 days
(d)100 days
Answer
Answer (as printed): C
Explanation
Let the required number of days be $x$. More distance, More days required (Direct Proportion) More speed, Less days required (Indirect Proportion) More resting hours, More days required (Direct Proportion) Distance $$\left.\begin{array}{l} 1: 2 \\ 2: 1 \\ 9: 18 \end{array}\right\}:: 40: x \begin{aligned} & \therefore \quad 1 \times 2 \times 9 \times x= \\ & 2 \times 1 \times 18 \times 40 \Leftrightarrow x=\frac{2 \times 18 \times 40}{2 \times 9}=80 . \end{aligned}$$
Explanation as extracted from the printed page; notation may be imperfect.