Aptitude - Time and Distance - Discussion
Discussion Forum : Time and Distance - General Questions (Q.No. 13)
13.
It takes eight hours for a 600 km journey, if 120 km is done by train and the rest by car. It takes 20 minutes more, if 200 km is done by train and the rest by car. The ratio of the speed of the train to that of the cars is:
Answer: Option
Explanation:
Let the speed of the train be x km/hr and that of the car be y km/hr.
| Then, | 120 | + | 480 | = 8  |
1 | + | 4 | = | 1 | ....(i) |
| x | y | x | y | 15 |
| And, | 200 | + | 400 | = | 25 | |
1 | + | 2 | = | 1 | ....(ii) |
| x | y | 3 | x | y | 24 |
Solving (i) and (ii), we get: x = 60 and y = 80.
Ratio of speeds = 60 : 80 = 3 : 4.
Discussion:
84 comments Page 2 of 9.
Karan said:
4 years ago
How that 200 and 400 comes? Please explain me.
(2)
Gopalakrishnan said:
4 years ago
Thanks @Ophi
Manthan Patel said:
4 years ago
Anyone please explain clearly.
(1)
Shoban said:
4 years ago
For those who are facing problems solving equation 1 & 2.
We got that,
eq 1: 1/x+4/y=1/15 =>1/x=1/15-4/y.
eq 2: 1/x+2/y=1/24 =>1/x=1/24-2/y.
Now equate the 1/x values.
i.e 1/15-4/y=1/24-2/y =>2/y=1/15-1/24
So you get y = 80.
By submitting y in the eq 1: 1/x+4/80=1/15 u get x =60.
X:Y= 60:80 =>3:4.
We got that,
eq 1: 1/x+4/y=1/15 =>1/x=1/15-4/y.
eq 2: 1/x+2/y=1/24 =>1/x=1/24-2/y.
Now equate the 1/x values.
i.e 1/15-4/y=1/24-2/y =>2/y=1/15-1/24
So you get y = 80.
By submitting y in the eq 1: 1/x+4/80=1/15 u get x =60.
X:Y= 60:80 =>3:4.
(10)
Deepu said:
5 years ago
Please, show how to solve equation 1 and 2 step by step? Anyone explain, please.
Akanksha said:
5 years ago
I didn't understand the step of solving the equation 1 and 2. Please someone explain me.
(2)
Vikky said:
5 years ago
Hello.
Here we can solve the equation 1 & 2 by multiplying equation 1 & 2 by number 2.
i.e. multiply eq 1 with 2 it becomes,
2/x + 8/y = 2/15,
Now multiply eq 2 with 2 we get,
2/x + 4/y = 2/24.
Now, solving eq 1 & 2.
i.e. subtract eq 2 from eq 1 we, get,
Eq 1 - Eq 2.
2/x + 8/y = 2/15.
-( 2/x + 4/y ) = -2/24.
By cancellation and sloving we get:
4/y = 2/15 - 2/24.
By taking L.C.M we, get;
4/y = (8-5)/60,
4/y = 1/20.
i.e.. y= 80 then substitute the value of y in eq1 or eq 2 u will get the value of X as 60
Then their ratio is 3:4.
Here we can solve the equation 1 & 2 by multiplying equation 1 & 2 by number 2.
i.e. multiply eq 1 with 2 it becomes,
2/x + 8/y = 2/15,
Now multiply eq 2 with 2 we get,
2/x + 4/y = 2/24.
Now, solving eq 1 & 2.
i.e. subtract eq 2 from eq 1 we, get,
Eq 1 - Eq 2.
2/x + 8/y = 2/15.
-( 2/x + 4/y ) = -2/24.
By cancellation and sloving we get:
4/y = 2/15 - 2/24.
By taking L.C.M we, get;
4/y = (8-5)/60,
4/y = 1/20.
i.e.. y= 80 then substitute the value of y in eq1 or eq 2 u will get the value of X as 60
Then their ratio is 3:4.
(2)
Asmita said:
5 years ago
How to slove eq1 and 2? please anyone explain.
(1)
Sainath said:
6 years ago
How did we got 25/3?
Juwel said:
6 years ago
It takes 4 hours for 300 km whereof 60 km is covered by train and the rest by car. It takes 20 min more if 100 km is covered by train and rest by car then what is the ration. Please explain.
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