A) 75 km
B) 150 km
C) 300 km
D) 600 km
Correct Answer: D
Solution :
(d): 600 km Let uniform speed be u and distance = d \[\frac{d}{u}=t\Rightarrow d=ut;\] Also, \[\frac{d}{u+10}=t-2;\frac{d}{u-10}=t+3\] \[\Rightarrow ut=(u+10)(t-2)\Rightarrow \cancel{ut}=\cancel{ut}+10t-2u-20\] \[\Rightarrow [\,u-5t=-10\,]\]?????????..(1) Also, \[\frac{ut}{u-10}=(t+3)\Rightarrow \cancel{ut}=\cancel{ut}-10t+3u-30\] \[\Rightarrow \,\,\,[\,3u-10t=30\,]\]????????.(2) From (1) and (2), \[5t=60\Rightarrow t=12\] And \[u=-10+60=50\] \[\therefore ut=50\times 12=600\]You need to login to perform this action.
You will be redirected in
3 sec