Question

Rahul and his friend Vishal went for a picnic to beautiful

destination Goa. They did boating. Rahul goes 30 km upstream and

44 km downstream in 10 hours. In 13 hours, Vishal goes 40 km

upstream and 55 km down-stream..

From this situation answer the following questions


i) How much total distance in km Vishal did boating ?

a) 74 b) 95 c) 70 d) 99


ii) Let the speed of the boat in still water be x km /hr and speed

of the stream y km/hr then what is the speed of the boat

downstream in km/hr?

a)(x - y) b) (x + y) c) xy d) x/y


iii) Let the speed of the boat in still water be x km /hr and speed of

the stream y km/hr then what is the speed of the upstream?

a) (x - y) b) (x + y) c) xy d) x/y


iv)

= …………..?


v) How much time taken by Vishal to go 30 km upstream ?

a) 44/(x + y) b) 44/(x – y) c) 30/(x – y) d) 30/(x – y)​

Answer 1

Answer :

i) option b

ii) option b

iii) option a

v) option c / d

Step-by-step explanation :

Given,

• Rahul goes 30 km upstream and  44 km downstream in 10 hours

• In 13 hours, Vishal goes 40 km  upstream and 55 km downstream

Solution,

[i] How much total distance in km Vishal did boating ?

   = distance covered upstream + distance covered downstream

   = 40 km + 55 km

   = 95 km

⇒ option (b)

[ii] The speed of the boat in still water be = x km/hr

    The speed of the stream = y km/hr

    Speed of the boat downstream = ?

The boat is flowing along the direction of the stream

So, net speed of the boat = speed of the boat in still water + speed of the stream

               = (x + y) km/hr

Therefore, The speed of the boat  downstream is (x + y) km/hr

⇒ option (b)

[iii] The speed of the boat in still water be = x km/hr

    The speed of the stream = y km/hr

    Speed of the boat upstream = ?

The boat is flowing in the opposite direction to the stream

So, net speed of the boat = speed of the boat in still water - speed of the stream

             = (x - y) km/hr

Therefore, The speed of the boat upstream is (x - y) km/hr

⇒ option (a)

[v] time taken by Vishal to go 30 km upstream = ?

       net speed of the boat upstream = speed of the boat in still water - speed of the stream

             = (x - y) km/hr

we know,

  speed = distance/time

  time = distance/speed

   time = 30 km/ (x - y) km/hr

   time = 30/(x - y) hr

⇒ option (c) / (d)