CBSE BOARD X, asked by dawar999, 5 months ago

Ritu can row downstream 20 km in hours and upstream 4 km in 2 hours. Find her speed of rowing in still water and the speed of the current.

Answers

Answered by sairam1919
74

Speed of boat = 6 Km/hr.

Speed of current = 4 Km/hr.

Upstream speed = x-y = 2 Km/hr.

Downstream speed = x + y = 10 Km/hr.

Step-by-step explanation:

Let speed of boat in still water = x km/hr

Let speed of stream = y km/hr

So Upstream speed = (x - y) km/hr

Downstream speed = (x + y) km/hr.

Given:  

Distance / speed = time.

So 20/x+y  = 2

2x + 2y = 20

Dividing by 2, we get x + y = 10 -------(1)

4/x-y = 2

2x - 2y = 4

Dividing by 2, we get x - y = 2 -------(2)

Adding (1) and (2), we get: 2x = 12

therefore x = 6

Substituting x in equation 2, we get 6 - y = 2  

Therefore y = 4

Speed of boat = 6 Km/hr.

Speed of current = 4 Km/hr.

Upstream speed = x-y = 2 Km/hr.

Downstream speed = x + y = 10 Km/hr.

Answered by SarcasticKarma
3

Answer:

Speed of boat = 6 Km/hr.

Speed of current = 4 Km/hr.

Upstream speed = x-y = 2 Km/hr.

Downstream speed = x + y = 10 Km/hr.

Step-by-step explanation:

Let speed of boat in still water = x km/hr

Let speed of stream = y km/hr

So Upstream speed = (x - y) km/hr

Downstream speed = (x + y) km/hr.

Given:  

Distance / speed = time.

So 20/x+y  = 2

2x + 2y = 20

Dividing by 2, we get x + y = 10 -------(1)

4/x-y = 2

2x - 2y = 4

Dividing by 2, we get x - y = 2 -------(2)

Adding (1) and (2), we get: 2x = 12

therefore x = 6

Substituting x in equation 2, we get 6 - y = 2  

Therefore y = 4

Speed of boat = 6 Km/hr.

Speed of current = 4 Km/hr.

Upstream speed = x-y = 2 Km/hr.

Downstream speed = x + y = 10 Km/hr.

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