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 11 of 12.
Poojith said:
4 years ago
1hr 40min and 48sec == 1.68hours.
5x/7 = 42/1.68,
5x/7 = 25.
5(25)/7 = 35km/hr.
5x/7 = 42/1.68,
5x/7 = 25.
5(25)/7 = 35km/hr.
(2)
Avi said:
4 years ago
Isn't Time = Distance/Speed why did they multiply?
Also explain the step : 5/7x*75/126.
Also explain the step : 5/7x*75/126.
(1)
Imtiaz said:
4 years ago
To convert the time 1 hr 40 min 48 sec to hours,
Hours = 1 + (40 ÷ 60) + (48 ÷ 3600),
Hours = 1 + 0.67 + 0.0134.
Hours = 1.68 hrs, which is nothing but 126/75.
Hours = 1 + (40 ÷ 60) + (48 ÷ 3600),
Hours = 1 + 0.67 + 0.0134.
Hours = 1.68 hrs, which is nothing but 126/75.
Sree ezhil said:
4 years ago
Simple method:
S1: covert seconds to minutes
48/60 =0.8min ; 40min+0.8min =40.8min.
S2: convert min to sec.
40.8/60 =0.68 ; 0.68hr+1hr= 1.68hr
S3: for avg speed
5/7 x= 42/1.68,
5/7x = 25,
x = 25 * 7/5,
x = 35.
Hope you guys understand easily.
S1: covert seconds to minutes
48/60 =0.8min ; 40min+0.8min =40.8min.
S2: convert min to sec.
40.8/60 =0.68 ; 0.68hr+1hr= 1.68hr
S3: for avg speed
5/7 x= 42/1.68,
5/7x = 25,
x = 25 * 7/5,
x = 35.
Hope you guys understand easily.
(84)
KUMARI SUPRITA said:
3 years ago
1hr + 40min + 48sec = 1 + (40/60) + (48/60*60).
= 1 + 2/3 + 1/75 = 126/75.
= 1 + 2/3 + 1/75 = 126/75.
(28)
Some people said:
3 years ago
How come 126? Please explain.
(11)
Vijay said:
3 years ago
Thanks @Siddharth.
(4)
Kailash said:
3 years ago
@Nikita,
Please solve and explain the following step.
(204/5)/60 = 51/75.
Like if I do (204/5)/60 = 4.8/60 = 0.08.
Please solve and explain the following step.
(204/5)/60 = 51/75.
Like if I do (204/5)/60 = 4.8/60 = 0.08.
(7)
Mohd younis said:
3 years ago
1hrs 40 min 48sec.
1 + 40/60 + 48/60 * 60 = 42/25 = 1.68 hours.
1 + 40/60 + 48/60 * 60 = 42/25 = 1.68 hours.
(32)
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)
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