Subject: General Aptitude · Chapter: Time and Distance · Exam: · Marks: · Difficulty:
$A, B$ and $C$ are on a trip by a car. $A$ drives during the first hour at an average speed of 50 km/hr. B drives during the next 2 hours at an average speed of 48 km/hr. $C$ drives for the next 3 hours at an average speed of 52 km/hr. They reached their destination after exactly 6 hours. Their mean speed was :
(a)50 km/hr
(b)$50 \frac{1}{3} \mathrm{km} / \mathrm{hr}$
(c)$51 \frac{1}{3} \mathrm{km} / \mathrm{hr}$
(d)52 km/hr
Answer
Answer (as printed): B
Explanation
Total distance travelled $=(50 \times 1+48 \times 2+52 \times 3) \mathrm{km}$ $$=302 \mathrm{km} .$$ Total time taken $=6 \mathrm{hrs}$. $$\text { ∴ Mean speed }=\left(\frac{302}{6}\right) \mathrm{km} / \mathrm{hr}=50 \frac{1}{3} \mathrm{km} / \mathrm{hr} .$$