Subject: General Aptitude · Chapter: Time and Distance · Exam: 2006 · Marks: · Difficulty:
How long must a driver take to drive the final 70 miles of a trip if he wants to average 50 miles an hour for the entire trip and during the first part of the trip he drove 50 miles in $1 \frac{1}{2}$ hours?
(a)54 min
(b)1 hour
(c)66 min
(d)70 min
Answer
Answer (as printed): A
Explanation
Total distance $=(70+50)$ miles $=120$ miles. Average speed = 50 miles/hour. Required time of journey $=\left(\frac{120}{50}\right) \mathrm{hr}=\frac{12}{5}=\mathrm{hr} 2 \frac{2}{5} \mathrm{hr}$ $=2 \mathrm{hr} 24 \mathrm{min}$. Time taken to cover 50 miles $=1 \frac{1}{2} \mathrm{hr}=1 \mathrm{hr} 30 \mathrm{min}$. ∴ Remaining time $=(2 \mathrm{hr} 24 \mathrm{min}-1 \mathrm{hr} 30 \mathrm{min})=54 \mathrm{min}$.