Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 31)
31.
Two, trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 9 hours and 16 hours respectively. The ratio of their speeds is:
Answer: Option
Explanation:
Let us name the trains as A and B. Then,
(A's speed) : (B's speed) = b : a = 16 : 9 = 4 : 3.
Discussion:
108 comments Page 11 of 11.
SAURABH SUMAN said:
1 decade ago
SIMPLY THEY ARE USING DISTANCE FORMULA DISTANCE=TIME*SPEED
Ashish said:
1 decade ago
Explain formula used.
Ishita Narula said:
1 decade ago
Suppose the total distance is x,
Time taken by trains to meet = t
if speeds be s1 and s2, and they meet after time t,
=> s1*t + s2*t =x (eqn 1)
Train A takes total t+9 hours to travel x with speed s1,
=> s1(t+9)=x (eqn 2)
for train B, total time t+16
=> s2(t+16)=x (eqn 3)
9*s1= t*s2 (equate eqn 1 and 2)
t*s1= 16*s2 (equate eqn 1 and 3)
divide,
9/t= t/16 => t*t= 9*16
substitute t,
=> s1/s2= sqre-root (16/9)
Time taken by trains to meet = t
if speeds be s1 and s2, and they meet after time t,
=> s1*t + s2*t =x (eqn 1)
Train A takes total t+9 hours to travel x with speed s1,
=> s1(t+9)=x (eqn 2)
for train B, total time t+16
=> s2(t+16)=x (eqn 3)
9*s1= t*s2 (equate eqn 1 and 2)
t*s1= 16*s2 (equate eqn 1 and 3)
divide,
9/t= t/16 => t*t= 9*16
substitute t,
=> s1/s2= sqre-root (16/9)
Karunakaran said:
1 decade ago
Let distance = x, a as speed of train a & b as speed of train b
9 x a = x
16 x b= x
9a = 16b
a/b = 16/9, simplify this with square root both up & down we get 4/3 & ratio 4:3.
9 x a = x
16 x b= x
9a = 16b
a/b = 16/9, simplify this with square root both up & down we get 4/3 & ratio 4:3.
PARTH said:
1 decade ago
Can someone prove that?
Kiran.p said:
1 decade ago
Vinod said:
1 decade ago
How can you calculate speed as the square-root of time?
Bhargav said:
2 decades ago
Speed = Distance/Time; Then how will you write root of time?
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