1
You visited us 1 times! Enjoying our articles? Unlock Full Access!
Question

# John covered a part of his journey at 20 kmph, and the remaining part at 70 kmph. He took a total of 8 hr to cover a distance of 400 km. For how much time did he travel at 20 kmph?

A
4 hr and 40 min
No worries! Weâ€˜ve got your back. Try BYJUâ€˜S free classes today!
B
4 hr and 12 min
No worries! Weâ€˜ve got your back. Try BYJUâ€˜S free classes today!
C
3 hr and 12 min
Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses
D
3 hr and 20 min
No worries! Weâ€˜ve got your back. Try BYJUâ€˜S free classes today!
Open in App
Solution

## The correct option is C 3 hr and 12 minLet the total time that John has travelled at the speed of 20 kmph be T. Distance is the product of speed and time. Hence, the distance covered at a speed of 20 kmph is: s1=20×T.........(i) The total time taken covered is 8 hr. Thus, the time to cover the remaining distance is: t2=8−T The remaining distance which is covered at a speed of 70 kmph is: s2=70×(8−T).......(ii) Given, the total distance covered: s=400 km.......(iii) But, s=s1+s2 From (i), (ii) and (iii), we get 400=20×T+70×(8−T) 50×T=160 T=3.2 hr We know 1 hr=60 min ⟹0.2 hr=0.2×60=12 min ∴T=3 hr and 12 min

Suggest Corrections
0
Join BYJU'S Learning Program
Related Videos
Unitary Method
MATHEMATICS
Watch in App
Explore more
Join BYJU'S Learning Program