Question

Study the pictures given. On the pairs of given pictures answer the questions related to this.
The speed of boat in still water is 11 km/h. It can go 12 km upstream and return downstream
to the original point in 2 hours 45 minutes. Assume that speed of stream is km/h.
(i) Total speed during upstream is
(a) (11 + ) km/h (b) km/h
(c) 11 km/h (d) (11 − ) km/h
(ii) Total speed during downstream is
(a) (11 + ) km/h (b) km/h
(c) 11 km/h (d) (11 − ) km/h
(iii) Speed of steam =
(a) 5 m/s (b) 15 m
(c) 5 km/h (d) 5 km
(iv) Time taken during upstream
(a) 45 min (b) 2 min
(c) 2 hr. (d) 2 hr. 45 min
(v) Time taken during downstream
(a) 45 min (b) 2 min
(c) 2 hr. (d) 2 hr. 45 mi

Answer 1

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World Environment Day is celebrated annually on 5 June and is the United Nations' principal vehicle for encouraging awareness and action for the protection of the environment.

Answer 2

Step-by-step explanation:

Answer

Let the speed of the stream be skm/hr.

Speed of boat in still water =11km/hr

Speed of boat in upstream =(11−s)km/hr

Speed of boat in downstream =(11+s)km/hr

Distance =12km

Therefore

11−s

12

+

11+s

12

=2

4

3

hr

⇒

(11−s)(11+s)

12(11+s+11−s)

=

4

11

⇒

121−s

2

12×22

=

4

11

⇒

121−s

2

12×2

=

4

1

⇒96=121−s

2

⇒s

2

=25

⇒s=±5

Since speed cannot be negative, we take s=5

Therefore Speed of stream is 5km/hr