A) 32km/hr
B) 40km/hr
C) 27km/hr
D) 44km/hr
Correct Answer: B
Solution :
Let the initial speed of car be x km per hour. Time taken to cover distance 200 km, \['{{t}_{1}}'\] \[=\frac{200}{x}\] Time taken to cover 200 km with increased speed \[{{t}_{2}}=\frac{200}{x+10}\] Now, \[{{t}_{1}}-{{t}_{2}}=1\] \[\therefore \,\,\frac{200}{x}-\frac{200}{x+10}=1\] \[\Rightarrow \,\,x(x+10)\,=2000\] \[\Rightarrow \,x(x+10)\,=40\times 50\] From here x = 40 km/hr. \[\therefore \] initial speed of the car is 40 km/hr.
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