Sunday, September 30, 2012

A man travels from A to B at 4 km/h and from B to A at 6 km/h. The total journey takes 45 minutes. Find the distance traveled.

Let the distance from A to B is
D


Then, the distance from B to A is also
D.


Let us use the distance formula to find
D.


We know that:


D = Speed *
Time


Given that the speed from A to B is S1 =
4


==> D = 4 * T1


Also
given that the speed from B to A is S2 = 6


==> D = 6
* T2


Then D = D


==> 4T1
= 6T2 .............(1)


But we know that the total time is
45 min


==> 45 min = 3/4
hour.


==> T1 + T2 =
3/4


We will substitute into
(1).


==> 4T1 = 6 ( 3/4 -
T1)


==> 4T1 = 9/2 -
6T1


==> 10T1 =
9/2


==> T1 = 9/20 = 0.45
hour


==> T2 = 3/4 - 9/20 = 6/20 = 0.3
hour


Then D = 4*T1 = 4* 0.45 = 1.8
km


Then, the distance is 1.8
km.

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