Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 10)
10.
A car travelling with 
of its actual speed covers 42 km in 1 hr 40 min 48 sec. Find the actual speed of the car.
of its actual speed covers 42 km in 1 hr 40 min 48 sec. Find the actual speed of the car.
Answer: Option
Explanation:
| Time taken = 1 hr 40 min 48 sec = 1 hr 40 | 4 | min = 1 | 51 | hrs = | 126 | hrs. |
| 5 | 75 | 75 |
Let the actual speed be x km/hr.
| Then, | 5 | x x | 126 | = 42 |
| 7 | 75 |
 x = |
 |
42 x 7 x 75 |  |
= 35 km/hr. |
| 5 x 126 |
Discussion:
117 comments Page 3 of 12.
Swetha said:
1 decade ago
Thanks nikita.
Dilip said:
1 decade ago
Wy to multiply 5/7 with 25?
Manish tiwari said:
1 decade ago
1 hr 40min 48 sec = 1 + 40/60 + 48/(60*60) hrs
=1+ 2/3 + 4/300
=(300+200+4)/300
=504/300
=126/75
Please sidharth can explain the answer please as 35 km/ph and =(300+200+4)/300 this step.
Thanks.
=1+ 2/3 + 4/300
=(300+200+4)/300
=504/300
=126/75
Please sidharth can explain the answer please as 35 km/ph and =(300+200+4)/300 this step.
Thanks.
Laxmi bhavani.B said:
1 decade ago
For converting
Min to hours:divide by 60
Sec to min:divide by 60
Aain Min to hours:divide by 60
so,
1 hr 40min 48sec= 1 + 40/60 + 48/(60*60) hrs
=1+ 2/3 + 4/300
=(300+200+4)/300
=504/300
=126/75
actual speed=X km/hr
Then
(5/7)X*(126/75)=42
X=(42*7*75)/(5*126)
=35Km/hr
Min to hours:divide by 60
Sec to min:divide by 60
Aain Min to hours:divide by 60
so,
1 hr 40min 48sec= 1 + 40/60 + 48/(60*60) hrs
=1+ 2/3 + 4/300
=(300+200+4)/300
=504/300
=126/75
actual speed=X km/hr
Then
(5/7)X*(126/75)=42
X=(42*7*75)/(5*126)
=35Km/hr
Shro said:
1 decade ago
@Abhishek
I din't understand 4th line..
= 1hr +(40.8/60)hr [as,(40.8/60)=(68/100)]
please explain it...
how 40.8/60= 68/100?
I din't understand 4th line..
= 1hr +(40.8/60)hr [as,(40.8/60)=(68/100)]
please explain it...
how 40.8/60= 68/100?
Anshu said:
1 decade ago
Let the actual speed be x
Total time = 1 hr 40 4/5 min .
= 1 51/75 hr.
= 126 / 75 hr
[convert it into min then into hrs by dividing it by 60
e.g 15 sec = 15/60 min = 1/4 min]
speed * time = distance
5/7x * 126/75 = 42
x = 42 x 75 x 7 / 5 x 126
x = 35
therefore
x = 35 kmph
Total time = 1 hr 40 4/5 min .
= 1 51/75 hr.
= 126 / 75 hr
[convert it into min then into hrs by dividing it by 60
e.g 15 sec = 15/60 min = 1/4 min]
speed * time = distance
5/7x * 126/75 = 42
x = 42 x 75 x 7 / 5 x 126
x = 35
therefore
x = 35 kmph
Shiva said:
1 decade ago
Conversion of km/hr to m/sec :
x km/hr = (x * (5/18)) m/sec
Conversion of m/sec to km/hr :
x m/sec = (x * (18/5)) km/hr
x km/hr = (x * (5/18)) m/sec
Conversion of m/sec to km/hr :
x m/sec = (x * (18/5)) km/hr
Srivastav said:
1 decade ago
Another method:
Let the original speed be x.
5/7 of the speed = 5x/7.
48 seconds = 48/3600 hours = 1/75 hours.
40 minutes = 40/60 =2/3 hours.
1 hour.
So total time in hours = 1+2/3 +1/75.
75+50+1 / 75=126/75 hours.
speed = distance / time.
speed = 42 / 126/75.
speed= 42*75/126.
5x/7= 25.
5x=25*7.
x= 25*7/5.
x=35.
x= 35 km/h.
Let the original speed be x.
5/7 of the speed = 5x/7.
48 seconds = 48/3600 hours = 1/75 hours.
40 minutes = 40/60 =2/3 hours.
1 hour.
So total time in hours = 1+2/3 +1/75.
75+50+1 / 75=126/75 hours.
speed = distance / time.
speed = 42 / 126/75.
speed= 42*75/126.
5x/7= 25.
5x=25*7.
x= 25*7/5.
x=35.
x= 35 km/h.
Anand Raj said:
1 decade ago
1 hr 40 min 48 sec = 1 + 40/60 + 48/(60*60) hrs.
= 1+ 2/3 + 4/300.
= 1+ (100/100)(2/3)+4/300.
= 1+ 200/300 + 4/300.
= (300/300)1 + 200/300 + 4/300.
= (300/300) +(200/300) +(4/300).
= (300/1 + 200/1 +4/1)/300.
= (300+200+4)/300.
= 504/300.
= 126/75.
= 1+ 2/3 + 4/300.
= 1+ (100/100)(2/3)+4/300.
= 1+ 200/300 + 4/300.
= (300/300)1 + 200/300 + 4/300.
= (300/300) +(200/300) +(4/300).
= (300/1 + 200/1 +4/1)/300.
= (300+200+4)/300.
= 504/300.
= 126/75.
Rahul said:
1 decade ago
From where 5/7came?
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