Quote:
Originally Posted by Quratulain04
A train running between two towns arrives at its destination 10 minutes late when it
goes 40 miles per hour and 16 minutes late when it goes 30 miles per hour. The
distance between the two towns is
A. 720 miles
B. 12 miles
C. 8-6/7 miles
D. 12-7/7 miles
E. None of these
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The answer is B,
Solution: This will be done by setting up two equations from
distance = Speed x Time travel
For 1st case: d = 40 x (t+10/60)-------- Eq. 1
this will become d= 40t + 400/60
For 2nd case: d= 30 x (t + 16/60)---------Eq. 2
this will become d= 30t + 480/60
Note: We take t+10/60 because in first case train reached 10minutes late and same for 2nd case
Now as both equation's L.H.S is same i.e d, therefore compare both equations by which we got
40t + 400/60 = 30t + 480/60
Now, solve this equation for t, like
40t-30t = 480/60 - 400/60
10t = 80/60
10t = 8/6
t= 8/6*10
t=8/60 or 8 Minutes (as we know that the hours is equal to 60 minutes, therefore 8/60 is equal to 8 Minutes)
Now put this value in either of equation
d= 40 x (t+10/60)
t= 8/60
d= 40 x (8/60 + 10/60)
d= 12 miles