Priya starts from A at 7.00 AM and reaches B at 10.00 PM. If Priya increased her speed by 10 km/hr, she would have reached B in 2.5 hours earlier. Find the time taken by Priya to cover a distance that is 250 km less than the distance between A and B with her initial speed.
a) 7.5 hours
b) 10 hours
c) 12 hours
d) None of these
Sol:
Let Distance between A and B = x km
Let Original speed of Priya = y km/hr
Then Increased speed of Priya = (y + 10) km/hr
Original time taken by Priya to cover the distance
between A and B = 7.00 AM – 10.00 PM = 15
hours
x/15 = y
x = 15y —- (1)
x/(y + 10) = 15 – 2.5
x/(y + 10) = 12.5 —- (2)
From (1) and (2),
15y = 12.5y + 125
2.5y = 125
y = 50 km/hr
x = 15 * 50 = 750 km
Required time taken = (750 – 250)/50 = 500/50 =
10 hours
