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 4 of 12.
Anand singh said:
6 years ago
Is there any short cut trick to directly convert second min in hrs.
Vrushali said:
6 years ago
By using formula S = D/T.
S=(5/7)x is the actual speed.
(5/7)x = 42/{1+(40÷60)+(48÷3600)} by using DST
(5/7)x = 42/{1+(2÷3)+(1÷75)} by dividing terms we got;
(5/7)x = 42/{1+[(150+3)÷225]},
(5/7)x = 42/{[225+153]÷225},
(5/7)x = (42 * 225)÷(225+153),
(5/7)x = (9420)÷(378),
x = (9420÷378)*(7/5).
By cancelling terms we got;
X = 1890 ÷ 54.
By dividing we got;
X = 35kmph.
S=(5/7)x is the actual speed.
(5/7)x = 42/{1+(40÷60)+(48÷3600)} by using DST
(5/7)x = 42/{1+(2÷3)+(1÷75)} by dividing terms we got;
(5/7)x = 42/{1+[(150+3)÷225]},
(5/7)x = 42/{[225+153]÷225},
(5/7)x = (42 * 225)÷(225+153),
(5/7)x = (9420)÷(378),
x = (9420÷378)*(7/5).
By cancelling terms we got;
X = 1890 ÷ 54.
By dividing we got;
X = 35kmph.
(1)
Goutham said:
6 years ago
Thanks @Nikita.
(1)
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)
Uday said:
7 years ago
1 hour= 60 mins.
40 mins= 40/60 =0.6667hr.
48 sec = 48/60*60= 0.01333 hr.
1 hr 40 mins 48 sec = 1.68 hr.
42km/1.68 hr => 25kmph.
5/7 = 25kmph.
25 * 7/5 = 35kmph.
40 mins= 40/60 =0.6667hr.
48 sec = 48/60*60= 0.01333 hr.
1 hr 40 mins 48 sec = 1.68 hr.
42km/1.68 hr => 25kmph.
5/7 = 25kmph.
25 * 7/5 = 35kmph.
Harshaa said:
7 years ago
1H 40M 48S.
First convert 48 sec to minutes min then 48/60 = 4/5.
Convert 40+4/5 nin to hours 51/75,
Then 1 51/75 = 126/75.
First convert 48 sec to minutes min then 48/60 = 4/5.
Convert 40+4/5 nin to hours 51/75,
Then 1 51/75 = 126/75.
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.
Radha Krishnan said:
7 years ago
@Kishor :
5+48/60
=> 5+4/5.
= 29/5.
5+48/60
=> 5+4/5.
= 29/5.
Murali said:
7 years ago
Thanks @Nikita.
Pradeep said:
7 years ago
How to convert 1 hrs 40 mins 48 sec in 4/7? Please tell me in detail.
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