Question

Vinod and Kaurvaki start travelling in the same direction at 8 km/h and 13 km/h, respectively. After 4 h, Vinod doubled his speed and Kaurvaki reduced his speed by 1 km/h and reached the destination together. How long did the entire journey last?

• A. 3 h
• B. 6 h
• C. 9 h
• D. 12 h

Answer 1

The correct option is C 9 h

Distance travelled by Vinod in 4 $h=8\times 4=32km$
And distance travelled by Kaurvaki in $4h=13\times 4=52km$
New speed of Vinod = 16 km/h
And also new speed of Kaurvaki = 12 km/h
Now, distance between Vinod and Kaurvaki = 52 km - 32 km = 20 km
Relative speed = 4 km/h
Time $=\frac{20}{4}=5h$
Total time 4 + 5 = 9 h.