Friday, March 1, 2013

At 11am John starts along a highway at 50mph then 15 minutes later,Jimmy drives same highway at 65mph when will Jimmy catch up with John?

We know that speed = distance
/time


==> Distance = speed *
time


==> D = S*T


We
will calculate the time needed foe both John and Jimmy to travel a certain
distance.


Then the distance for both is the same and we
will assume it is D.


Now, we know that Jogns speed = 50
mph


==> S1= 50
mph


==> The time to travel D is
T1


==> D = 50 *
T1............(1)


Now we will determine the equation for
Jimmy.


The speed for Jimmy is S2 = 65
mph


The time needed to travel D is
T2


But we know that Jimmy left 15 minutes later after
John.


==> T2 = T1 - 15
minutes


15 minutes = 0.25
hour


==> T2 = T1 -
0.25


==> D = 65*(T1-
0.25)...........(2)


Now we will solve (1) and
(2).


==> 50*T1 = 65*(T1 -
0.25)


==> 50T1 = 65T1 -
16.25


==> 15*T1 =
16.25


==> T1 = 16.25 / 15
=13/12


13/12 hours = 1 1/12 hours = 1 hour and 5
minutes


Then Jimmy will catch up with John after one hour
and 12 minutes since John left.


John left at
11.


Then 11 + 1:05 =
12:05pm


Then Jimmy will catch up with John at
12:05 pm.

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