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 2 of 12.
Priyadharshini G said:
7 years ago
Given:
Let actual speed be x.
Speed=(5/7)x
Time=1 hr 40 min 48 sec.
Now, lets convert time into hours as a whole.
48 sec=48/60 min = 0.8 min
->40+0.8=40.8 min
->40.8 min=40.8/60 hr
=0.68 hr.
->1 hr+0.68 hr=1.68 hr.
Now, we know that speed=distance/time.
(5/7)x=42/1.68.
x = (42/1.68)*(7/5),
= (4200/168)*(7/5),
= 35 km/hr.
Let actual speed be x.
Speed=(5/7)x
Time=1 hr 40 min 48 sec.
Now, lets convert time into hours as a whole.
48 sec=48/60 min = 0.8 min
->40+0.8=40.8 min
->40.8 min=40.8/60 hr
=0.68 hr.
->1 hr+0.68 hr=1.68 hr.
Now, we know that speed=distance/time.
(5/7)x=42/1.68.
x = (42/1.68)*(7/5),
= (4200/168)*(7/5),
= 35 km/hr.
Jenny said:
2 years ago
As the ratio of the car's own speed is given;
5 is the new speed of the car and 7 is the old speed of the car.
As the distance is constant;
The ratio of time is reverse that is 7:5
Thus if 7 = 100.8 (hours into minutes).
1 = 14.4.
5 = 72.
Convert this into an hour, you will get 1.2.
42km distance divided by 1.2 times = 35kmph.
5 is the new speed of the car and 7 is the old speed of the car.
As the distance is constant;
The ratio of time is reverse that is 7:5
Thus if 7 = 100.8 (hours into minutes).
1 = 14.4.
5 = 72.
Convert this into an hour, you will get 1.2.
42km distance divided by 1.2 times = 35kmph.
(15)
Sherief said:
2 years ago
Simplest form;
S = D ÷ T formula;
S = 5s ÷ 7.
42km~convert in meter so, 4200.
1hr+40min+48sec.
= (60min × 60sec) + (40min × 60sec) + 48sec,
= 6048.
S = D÷T.
5s ÷ 7 = 4200 ÷ 6048.
= 4200×7 ÷ 6048 ÷ 5
= 8400 ÷ 864,
= 350 ÷ 36.
To change in m/s to km/hr so;
= (350÷36)×18÷5.
= 35km/hr answer.
S = D ÷ T formula;
S = 5s ÷ 7.
42km~convert in meter so, 4200.
1hr+40min+48sec.
= (60min × 60sec) + (40min × 60sec) + 48sec,
= 6048.
S = D÷T.
5s ÷ 7 = 4200 ÷ 6048.
= 4200×7 ÷ 6048 ÷ 5
= 8400 ÷ 864,
= 350 ÷ 36.
To change in m/s to km/hr so;
= (350÷36)×18÷5.
= 35km/hr answer.
(48)
Vikram said:
10 years ago
Hai @Ruchir.
Given time is: 1 hr 40 min 48 sec.
Conver hr to sec.
First convert hr to min : 1 hr = 60 min.
Next convert min to sec : 60 min = 3600 sec (1 min = 60 sec).
Finally 1 hr = 3600 sec.
Convert min to sec.
40 min = 40*60 sec = 2400 sec.
Then add 3600+2400+48 = 6048 sec.
1 hr 40 min 48 sec = 6048 sec.
Given time is: 1 hr 40 min 48 sec.
Conver hr to sec.
First convert hr to min : 1 hr = 60 min.
Next convert min to sec : 60 min = 3600 sec (1 min = 60 sec).
Finally 1 hr = 3600 sec.
Convert min to sec.
40 min = 40*60 sec = 2400 sec.
Then add 3600+2400+48 = 6048 sec.
1 hr 40 min 48 sec = 6048 sec.
Dipali jawale said:
5 years ago
1 Hr 40 Min 48 Sec => 1.68 Hr
Step by step explanation :
1 Hr = 60 Mins.
So,
1 Hr = 1 Hr
40 min = 40/60 hr = 2/3 hr.
1 Min = 60 Sec = 1/ 60 Hr.
1 Sec = 1/ 60 Min = 1/ 3600 Hr.
So,
48 Sec = 48/ 3600 Hr = 1/75 Hr
1 Hr 40 Min 48 Sec.
=> 1 + (2/3) + (1/75)
=> (75 + 50 + 1)/75
=> (126/75) Hr.
=> 1.8 Hr.
Step by step explanation :
1 Hr = 60 Mins.
So,
1 Hr = 1 Hr
40 min = 40/60 hr = 2/3 hr.
1 Min = 60 Sec = 1/ 60 Hr.
1 Sec = 1/ 60 Min = 1/ 3600 Hr.
So,
48 Sec = 48/ 3600 Hr = 1/75 Hr
1 Hr 40 Min 48 Sec.
=> 1 + (2/3) + (1/75)
=> (75 + 50 + 1)/75
=> (126/75) Hr.
=> 1.8 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.
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
Dheepak ts said:
1 decade ago
Easy method to convert timings:
First convert everything into seconds.
1 hour 40 mins 48 secs.
= 60*60+40*60+48 secs = 3600+2400+48 secs
= 6048 secs.
Now convert secs to hour by dividing it by 60*60 i.e. 3600.
6048/3600 = 42/25 hours you will get.
Apply it in D = S*T.
First convert everything into seconds.
1 hour 40 mins 48 secs.
= 60*60+40*60+48 secs = 3600+2400+48 secs
= 6048 secs.
Now convert secs to hour by dividing it by 60*60 i.e. 3600.
6048/3600 = 42/25 hours you will get.
Apply it in D = S*T.
Avi goyal said:
9 years ago
Time = 1 hr 40 min 48 sec.
= 1hr + 40/60hr + 48/3600 hr = 1 + 2/3 + 1/75 = 126/75 hr.
Distance = 42 km.
Speed = distance/time = 42/(126/75) = 42 * 75/126.
5/7 of the actual speed = 42 * 75/126.
Actual speed = 42 * 75/126 * 7/5.
= 42 * 15/18.
= 7 * 15/3.
= 7 * 5 = 35 km/hr.
= 1hr + 40/60hr + 48/3600 hr = 1 + 2/3 + 1/75 = 126/75 hr.
Distance = 42 km.
Speed = distance/time = 42/(126/75) = 42 * 75/126.
5/7 of the actual speed = 42 * 75/126.
Actual speed = 42 * 75/126 * 7/5.
= 42 * 15/18.
= 7 * 15/3.
= 7 * 5 = 35 km/hr.
Sunil pawar said:
7 years ago
@All.
In simple method;
1 hour +40min +48 sec, we have to convert it to an hour.
1+(40/60)+(48/60*60),
1+2/3+(1/75),
=(75+2*25+1)/75,
=126/75.
Now speed * time = distance,
5x/7 * 126/75 = 42 , x is the actual speed of car,
Solving this will give answer x = 35.
In simple method;
1 hour +40min +48 sec, we have to convert it to an hour.
1+(40/60)+(48/60*60),
1+2/3+(1/75),
=(75+2*25+1)/75,
=126/75.
Now speed * time = distance,
5x/7 * 126/75 = 42 , x is the actual speed of car,
Solving this will give answer x = 35.
(1)
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