Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 9)
9.
A man on tour travels first 160 km at 64 km/hr and the next 160 km at 80 km/hr. The average speed for the first 320 km of the tour is:
Answer: Option
Explanation:
| Total time taken = |  |
160 | + | 160 |  hrs. |
= | 9 | hrs. |
| 64 | 80 | 2 |
 Average speed = |
|
320 x | 2 | km/hr |
= 71.11 km/hr. |
| 9 |
Discussion:
63 comments Page 2 of 7.
Prashant said:
4 years ago
For 1st 160km time taken will be =160/64 = 2.5 sec.
For 2nd 160km time taken will be = 160/80 = 2 sec.
Total time taken in journey = 2.5 + 2 = 4.5 sec.
The avg speed for 320 km will be=total distance travelled/total time.
So,, 320/4.5 = 71.11 kmph.
For 2nd 160km time taken will be = 160/80 = 2 sec.
Total time taken in journey = 2.5 + 2 = 4.5 sec.
The avg speed for 320 km will be=total distance travelled/total time.
So,, 320/4.5 = 71.11 kmph.
(34)
Paarth said:
4 years ago
First 160 km: Speed is 64 kmph.
Second 160 km:- Speed is 80 kmph.
So, just use Average speed = (2xy)/x+y = (2*64*80)/64+80 = 71.11 kmph.
Second 160 km:- Speed is 80 kmph.
So, just use Average speed = (2xy)/x+y = (2*64*80)/64+80 = 71.11 kmph.
(2)
Rahul said:
5 years ago
Thanks @Sundar.
Vijayalakshmi V said:
5 years ago
The average speed = 2xy/(x+y).
where x=64 kmph y = 80 kmph,
Therefore, 2(64)(80)/(64+80) = (8)(80)/9.
= 640/9.
= 71.11 kmph.
where x=64 kmph y = 80 kmph,
Therefore, 2(64)(80)/(64+80) = (8)(80)/9.
= 640/9.
= 71.11 kmph.
(1)
Nishit said:
6 years ago
@All.
Average speed means time is constant. So time would be same. Right?
Average speed means time is constant. So time would be same. Right?
Ravi said:
6 years ago
At 64 km/hr it will take 2.5 hrs for travelling 1st 160 km and at 80 km/hr it will take 2 hrs for travelling 2nd 160 km.
So, the total 4.5 hrs for 320 km.
So 320 / 4.5 === 71.11 km Average speed.
So, the total 4.5 hrs for 320 km.
So 320 / 4.5 === 71.11 km Average speed.
(1)
Akshay Patel said:
6 years ago
Avg speed of x and y be x+y/2.
Then given that 64+80/2=72.
Then given that 64+80/2=72.
Aryan said:
7 years ago
How did 9/2 came? please explain me.
Girish said:
7 years ago
Well explanation, Thanks.
Kiran said:
7 years ago
Thanks, @Sundar.
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