Question

Time taken by a boat to civer (d-11)km in upstream is 5 times of the time taken by boat to cover (d-21) km in downstream if ratio of speed of boat in downstream is 1:3 and boat can cover (d-8)km in upstream in 14h find speed of boat in still water

Answer 1

Answer:

B=4

Explanation:

C=x

ds=3x

B=2x

us=x

D-11/x=5(D-21)/3x

=>D=36

x=(D-8)/14

=>x=2

hence, B=2x =>4

Answer 2

The speed of boat in still water is 4km per hour.

Explanation:

Time taken in rowing the boat upstream = Five times the time taken in rowing boat downstream.

Distance in upstream = d -11 km

Distance in downstream = d-21 km

From the above given values we can find the value of “D” let time taken in downstream be x

                             $\frac{(d-11)}{x} = \frac{(5(d-21))}{3x}$

On solving we get,

                          ⇒ 3d-33 = 5d-105

                              ⇒ 2d = 72

                              ⇒ d =36

So now finding value of speed in still water,

                            ⇒ x = $\frac{(d-8)}{14}$

                                  ⇒ x =2

Since, the speed in still water will be 2x ⇒ 4 km.

To know more:

The speed of a boat in still water is 8km/h. It can go 15 km upstream and 22 km downstream in 5 hours. Find the speed of the stream.

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