A sailor goes 8 km downstream in 420 minutes and returns in 1 hour. Fi

1.	A sailor goes 8 km downstream in 420 minutes and returns in 1 hour. Find the speed of the sailor in still water and the speed of the current .
Answer» Let the speed of the sailor in still water be x km/h and that of the current y km/h. Speed downstream = (x + y) km/h Speed upstream = (x – y) km/h As per the question (x + y) × 40/60 = 8 ⇒ x + y = 12 ………(i) When the sailor goes upstream, then (x – y) × 1 = 8 x – y = 8 ………(ii) Adding (i) and (ii), we get 2x = 20 ⇒ x = 10 Putting x = 10 in (i), we have 10 + y = 12 ⇒ y = 2 Hence, the speeds of the sailor in still water and the current are 10 km/h and 2 km/h respectively

A sailor goes 8 km downstream in 420 minutes and returns in 1 hour. Find the speed of the sailor in still water and the speed of the current .

Answer»

Let the speed of the sailor in still water be x km/h and that of the current y km/h.

Speed downstream = (x + y) km/h

Speed upstream = (x – y) km/h

As per the question

(x + y) × 40/60 = 8

⇒ x + y = 12 ………(i)

When the sailor goes upstream, then

(x – y) × 1 = 8

x – y = 8 ………(ii)

Adding (i) and (ii), we get

2x = 20

⇒ x = 10

Putting x = 10 in (i), we have

10 + y = 12

⇒ y = 2

Hence, the speeds of the sailor in still water and the current are 10 km/h and 2 km/h respectively