6 Views

Question : Sohan makes four journeys of equal distance. In the first journey, his speed was 240 km/hr and in each subsequent journey his speed was half the speed of the previous journey. What is the average speed of Sohan in these four journeys?

Option 1: 50 km/hr

Option 2: 64 km/hr

Option 3: 60 km/hr

Option 4: 52 km/hr


Team Careers360 25th Jan, 2024
Answer (1)
Team Careers360 27th Jan, 2024

Correct Answer: 64 km/hr


Solution : Let the distance of each trip be $d$.
For the first trip,
speed = 240 km/hr
$\therefore$ time = $\frac{d}{240}$
For the second trip,
speed = $\frac{240}{2}$ = 120 km/hr
$\therefore$ time = $\frac{d}{120}$
For the third trip,
speed = $\frac{120}{2}$ = 60 km/hr
$\therefore$ time = $\frac{d}{60}$
For the fourth trip,
speed = $\frac{60}{2}$ = 30 km/hr
$\therefore$ time = $\frac{d}{30}$
Average speed = $\frac{\text{total distance}}{\text{total time}}$
= $\frac{d+d+d+d}{\frac{d}{240}+\frac{d}{120}+\frac{d}{60}+\frac{d}{30}}$
= $\frac{4d}{\frac{15d}{240}}$
= $\frac{960}{15}$
= 64 km/hr
Hence, the correct answer is 64 km/hr.

Know More About

Related Questions

TOEFL ® Registrations 2024
Apply
Accepted by more than 11,000 universities in over 150 countries worldwide
Manipal Online M.Com Admissions
Apply
Apply for Online M.Com from Manipal University
GRE ® Registrations 2024
Apply
Apply for GRE® Test now & save 10% with ApplyShop Gift Card | World's most used Admission Test for Graduate & Professional Schools
View All Application Forms

Download the Careers360 App on your Android phone

Regular exam updates, QnA, Predictors, College Applications & E-books now on your Mobile

150M+ Students
30,000+ Colleges
500+ Exams
1500+ E-books