cramya wrote:Up stream
Distance - > 90
speed-> v-3
time-> t+1/2 = 2t+1/2
90 = 2t+1/2 (v-3)
180/(2t+1) - 3 = v (1)
Downstream
Distance - > 90
speed-> v+3
time-> t
90 = t(v+3)
90/t-3 = v (2)
Equate both v's from 1) and 2)
180/(2t+1) - 3 = 90/t-3
4t^2+2t-30 = 0
t=2.5
cramya, something wrong with your calculation, I'm confused ..
let me do it step by step..
up : v-3= 90/(t+1/2)
v = 90/(t+1/2) +3
(not -3)
v = 180/(t+1) +3 ------(1)
down: v+3= 90/t
v= 90/t -3 ----------(2)
180/(t+1)+3 = 90/t-3
180/(t+1)+9 = 90/t
180t/(t+1)+ 9t = 90
180t + 18t^2+9t =180t+90
18t^2+9t-90 = 0
2t^2+t-10=0 until here and I stopped.. could you tell me what is wrong??
