Correct Answer - Option 1 : 8.9 hr
Given:
A takes 5 hours to travel 320 km while B takes 7 hours to travel 301 km.
Formula Used:
Distance = time x speed
Calculation:
Speed A = (320/5) km/hr = 64 km/hr
Speed of B = (301/7) km/hr = 43 km/hr
Now, distance covered by B in 19 hours after reducing his speed by 13 km/hr = (30 × 19) km = 570 km.
Time required = (570/64) hours = 8.9 hours
∴ A will take 8.9 hours.