A takes 2 hours more than B to cover a distance of 40 km. If A doubles his speed, he takes 11/2 hours more than B to cover 80 km. To cover a distance of 90 km, how much time will B take travelling at his same speed?

Answer: Option B

Solution

Answer: Option B

Solution:

Distance same
Speed = 1 : 2
Time = 2 : 1
1 unit → 2.5
2 unit → 2 × 2.5 = 5 hr
A = 5 hr
B = 1 hr
Speed of B = $$=\frac{80}{1}$$ = 80 km/hr
Time $$=\frac{90}{80}=1\frac{1}{8}\text{hr}$$