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:
109 comments Page 11 of 11.
NANI said:
1 decade ago
Here in this question, one train had reached in 9 hrs and another one in 16 hrs.The first train reached faster than the second one ,clearly it should have more speed than the second one, as we know that time and speed are inversely proportional and comparing all answers, 4:3 is most optimal.
(1)
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:
2 decades ago
Vinod said:
2 decades 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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