Question

Length of train is 150 m. Its speed
is 60 km/h. In what time it will
cross an electric pole ?
INet & Haz., 2007-08)
(a) 3 sec
(b) 5 sec
(c) 9 sec
(d) 12 sec
A boat is rowed downstream at 15:5
km/hr and upstream at 8-5 km/hr
The speed of the stream is :
(SSC. 2005)​

Answer 1

s=distance/time

let stream speed be x and that of boat be y

upstream x-y=8.5

downstream. x+y=15.5

after eliminating y

2x=24. (y gets eliminated and x+x is 2x and 8.5+15.5 is 24)

so x or stream speed is 12 km/hr