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 9 of 12.
Nilesh R said:
1 decade ago
Is there any another method to solve this type of problem?
Shreya said:
1 decade ago
Is there any shortcut for conversion of time?
Pooja said:
1 decade ago
John starts at a specific time from home to his son's school and reach there at 4pm at the time his son's school ends. But one day the school ended up at 3pm and the boy started walking towards the home without waiting for his father. His david as regularly went to pick him up and they both met on the road and reached home 20 mins before the regular reaching time at home. So for who much time did the son walked from school towards his home.
Maddy nikam said:
1 decade ago
1hr 40m = 100 m.
42km/100m = 420 mtr/min.
60min*420 mtr = 25.20kmph.
2520*(7/5) = 35 kmph.
42km/100m = 420 mtr/min.
60min*420 mtr = 25.20kmph.
2520*(7/5) = 35 kmph.
Tisha said:
1 decade ago
first convert the time in hours format,
i.e 1 hour 40 mins 48 secs = 1+(40/60)+(48/(60*60)) = 126/75.
Hence time = 126/75 hrs,
w.k.t, s = d/t;
s = 42/ (126/75) (5/7).
s = 35 km/hr.
i.e 1 hour 40 mins 48 secs = 1+(40/60)+(48/(60*60)) = 126/75.
Hence time = 126/75 hrs,
w.k.t, s = d/t;
s = 42/ (126/75) (5/7).
s = 35 km/hr.
Arul Shalom said:
1 decade ago
Why don't we do it 1 step at a time.
1. Convert the sec into mts => 48 sec = 48/60 mts => 4/5 mts.
2. Now you have 1 Hr 40 mts + 4/5 mts. i,e: 1 hr 40 4/5 mts.
3. Convert mts into hr => 40 4/5 mts = (40 4/5)/60 hrs => 17/25 hr.
Therefore, 1 Hr 40 mts 48 sec is equal to 1 17/25 hrs => 1.68 hrs.
1. Convert the sec into mts => 48 sec = 48/60 mts => 4/5 mts.
2. Now you have 1 Hr 40 mts + 4/5 mts. i,e: 1 hr 40 4/5 mts.
3. Convert mts into hr => 40 4/5 mts = (40 4/5)/60 hrs => 17/25 hr.
Therefore, 1 Hr 40 mts 48 sec is equal to 1 17/25 hrs => 1.68 hrs.
Gandhi said:
1 decade ago
First convert 48 sec into minutes i.e=> 48/60=4/5 min.
Second 40 min and 4/5 min..convert them into hrs=>
(5*40+4)/(5*60) => 51/75 hrs.
Third step anyway 1 hr is an hr and 51/75 hrs => 1hr 51/75 => 126/75.
Second 40 min and 4/5 min..convert them into hrs=>
(5*40+4)/(5*60) => 51/75 hrs.
Third step anyway 1 hr is an hr and 51/75 hrs => 1hr 51/75 => 126/75.
Rahul said:
1 decade ago
From where 5/7came?
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.
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.
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