Two boats on the opposite shores of a river start moving toward each other. When they pass each other they are 750 yards from one shoreline. They each continue to the opposite shore, immediately turn around and start back. When they meet again they are 250 yards from the other shoreline. Each boat maintains a constant speed throughout. How wide was the river?

ধরি,
একটি জাহাজ A speed - এ যাচ্ছে এবং অপরটি B speed এ যাচ্ছে।
নদীর প্রস্থ w
At time = t₁
A (t₁) = 750
B(t₁) =(w - 750)
⇒ B/A = (w - 750)/750
750B = (w - 750)A
At time = t₂
A(t₂) = w + 250
B(t₂) = w +(w - 250)
= 2w - 250
⇒ B/A = (2w - 250)/(w + 250)
(w + 250)B = (2w - 250)A .... Eq.[1]
750B = (w - 750/A
B = [(w - 750)/750]A
Plug into Eq. [1]
(w + 250)[(w - 750)/750]A = (2w - 250) A
(w + 250)(w - 750)/750 =750(2w -250)
w² - 500w - 187,500 = 1500w - 187500
w2 - 2000w = 0
w2 = 2000w
w = 2000 yards.