Question

a boat moves from p to q (downstream) in 2.5 h and from q to p (upstream) in 5 h respectively when the engie is producing maximum speed on the boat in each case . if due to increased water flow the speed of flow of the river gets doubled how long will it take the boat(moving with possible speed) to move from

(a) p to q (downstream) (b) q to p (upstream)

Answer 1

let distance be d..let boat speed be v_b ,,and river speed be v_r
now for upstream v_b - v_r = d/5
and for downstream v_b + v_r = d/2.5 = 2d/5
on solving , v_b = 3d/10 and v_r = d/10
now new speed of river,v_R = 2d/10 =d/5
let unknown times be t_d and t_u
again,,for downstream,, v_b + v_R = d /t_d => substitute values and find t_d
and for upstream, v_b - v_R = d/t_u => subst. values and find t_u

Answer 2

it is 3d/5 is it??

Answer 3

what is 3d/5 ?

Answer 4

2d/5+d/5=3d/5

Answer 5

well (2v_b)= 3d/5 ..

Answer 6

wat? am i correct

Answer 7

am not getting what you're asking ?

Answer 8

v_b - v_r = d/5
and for downstream v_b + v_r = d/2.5 = 2d/5
on solving , v_b = 3d/10 and v_r = d/10

Answer 9

v_b=3/5 is it?

Answer 10

d is not given,,how can you say 3d/10 = 3/5

Answer 11

sorry it 3d/5

Answer 12

its 3d/10 !! how in this world you come up with 3d/5