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.
NANDHINI V said:
9 months ago
Let's take the actual speed as X,
So,
The travelling speed is 5x/7,
Distance d = 42km,
Time t=1hr 40min 48sec is written as 126/75,
Now we need to find the actual speed,
We know the formula,
T = D/S,
126/75 = 42/5x/7,
126/75 = 42 * 7/5x,
5x = 42 * 7 * 75/126,
x = 35km/hr.
So,
The travelling speed is 5x/7,
Distance d = 42km,
Time t=1hr 40min 48sec is written as 126/75,
Now we need to find the actual speed,
We know the formula,
T = D/S,
126/75 = 42/5x/7,
126/75 = 42 * 7/5x,
5x = 42 * 7 * 75/126,
x = 35km/hr.
(9)
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
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)
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.
Tejaswini said:
5 years ago
Convert km to m & hours to secs.
42km = 42000m.
1hr 40m 48s=1hr + 40mins + 38s.
(60*60) + (40*60) + 38.
6048s.
Let the speed be S.
5/7 S=42000/6048 m/s.
S=(42000*7)/(6048*5) m/s.
S=175/18 m/s.
Converting to kmph.
S=(175*18)/(18*5) kmph.
S=35 kmph.
42km = 42000m.
1hr 40m 48s=1hr + 40mins + 38s.
(60*60) + (40*60) + 38.
6048s.
Let the speed be S.
5/7 S=42000/6048 m/s.
S=(42000*7)/(6048*5) m/s.
S=175/18 m/s.
Converting to kmph.
S=(175*18)/(18*5) kmph.
S=35 kmph.
Soumava Bhattacharjee said:
6 years ago
Time Taken=1 hr 40 min 48 sec = 3600+(40x60)+48 = 6048 sec
Distance = 42 km = (42x1000) = 42000 m
Let the Actual Speed be = x m/sec
(5/7)x*6048 = 42000
x = 175*7/126 m/sec
x = (175*7*18)/(126*5) km/hr.
= 35 km/hr (OPTION D)
Distance = 42 km = (42x1000) = 42000 m
Let the Actual Speed be = x m/sec
(5/7)x*6048 = 42000
x = 175*7/126 m/sec
x = (175*7*18)/(126*5) km/hr.
= 35 km/hr (OPTION D)
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.
Rakeshgatla jgtl said:
9 years ago
Hello, clear your doubts with my explanations 40 minutes 40/60 = 2/3 and take 48 seconds.
48 / 60 * 60 = 1/75.
1 hour 40 minutes 48 seconds = 1 + 2/3 + 1/75 = 126/75 = 42/25.
Clear your doubts with my explanations.
48 / 60 * 60 = 1/75.
1 hour 40 minutes 48 seconds = 1 + 2/3 + 1/75 = 126/75 = 42/25.
Clear your doubts with my explanations.
Chetan said:
9 years ago
Speed * time = distance.
Let assume Actual speed be = x,
Distance = 42,
Time = 1 + (40÷60) + (48÷ 3600) = 1.68,
Hence 5x/7* 1.68 = 42,
5x/7 = 42/1.68,
5x/7 = 25,
5x = 25 * 7,
5x = 175,
X = 175/5,
And X = 35.
Let assume Actual speed be = x,
Distance = 42,
Time = 1 + (40÷60) + (48÷ 3600) = 1.68,
Hence 5x/7* 1.68 = 42,
5x/7 = 42/1.68,
5x/7 = 25,
5x = 25 * 7,
5x = 175,
X = 175/5,
And X = 35.
Sandeep Ippakayala said:
8 years ago
5/7u=42/1+2/3+1/75,
5/7u=42/126/75,
5/7u=42*75/126,
5/7u=3150/126,
5*126u=3150 * 7,
630u=22050,
u = 35KM.
Time in Hours:
1*75/75+2*25/3*25+1/75.
75+50+1/75.
126/75.
1hr=60min.
1/60hr=1min.
1min=60sec.
1/60min=1sec.
5/7u=42/126/75,
5/7u=42*75/126,
5/7u=3150/126,
5*126u=3150 * 7,
630u=22050,
u = 35KM.
Time in Hours:
1*75/75+2*25/3*25+1/75.
75+50+1/75.
126/75.
1hr=60min.
1/60hr=1min.
1min=60sec.
1/60min=1sec.
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