Subject: General Aptitude · Chapter: Time and Distance · Exam: · Marks: · Difficulty:
A man travels 600 km by train at 80 km/hr, 800 km by ship at 40 km/hr, 500 km by aeroplane at 400 km/hr and 100 km by car at 50 km/hr. What is the average speed for the entire distance?
(a)60 km/hr
(b)$60 \frac{5}{123} \mathrm{km} / \mathrm{hr}$
(c)62 km/hr
(d)$65 \frac{5}{123} \mathrm{km} / \mathrm{hr}$
Answer
Answer (as printed): D
Explanation
Total distance travelled $=(600+800+500+100) \mathrm{km}$ $$\text { = } 2000 \text { km. }$$ $$\text { Total time taken }=\left(\frac{600}{80}+\frac{800}{40}+\frac{500}{400}+\frac{100}{50}\right) \mathrm{hrs}=\frac{123}{4} \mathrm{hrs} .$$ $$\begin{aligned} \therefore \text { Average speed } & =\left(2000 \times \frac{4}{123}\right) \mathrm{km} / \mathrm{hr}=\left(\frac{8000}{123}\right) \mathrm{km} / \mathrm{hr} \\ & =65 \frac{5}{123} \mathrm{km} / \mathrm{hr} . \end{aligned}$$