Question

a steamer is going downstream in a river cover distance between two ports in 12 hrs . coming back upstream , it covers this distance in 18 hrs . the speed of water is 4 km/hr . find the speed of boat
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Answer 1

$\huge\boxed{\underline{\sf{\red{ᴀ}\green{ɴ}\pink{s}\orange{ᴡ}\blue{ᴇ}\pink{ʀ}}}}$

Given :-

a steamer is going downstream in a river cover distance between two ports in 12 hrs . coming back upstream , it covers this distance in 18 hrs . the speed of water is 4 km/hr

To Find :-

Speed of boat

Solution :-

Let the speed of boat be x km/hr

Now

When come upstream

x - 4 km/hr

When come downstream

x + 4 km/hr

Time to go downstream = 12 hr

Time to come upstream = 18 hr

Now,

S = D/T

S is the Speed

D is the Distance

T is the Time

Downstream = s/12 = (x + 4)

Upstream = s/18 = (x - 4)

s/18 × 12/s = (x + 4)/(x - 4)

18/12 = (x + 4)/(x - 4)

9/6 = (x + 4)/(x - 4)

6(x + 4) = 9(x - 4)

6x + 24 = 9x - 36

9x - 6x = 36 + 24

3x = 60

x = 20

Speed = 20 km/h

Answer 2

$\huge{ \boxed{ \sf \: Given :-}}$

a steamer is going downstream in a river cover distance between two ports in 12 hrs . coming back upstream , it covers this distance in 18 hrs . the speed of water is 4 km/hr

$\huge { \boxed{ \sf \: To \: \: Find :-}}$

Speed of boat

$\huge \pink{ \sf \: Solution :-}$

Let the speed of boat be x km/hr

Now

When come upstream

x - 4 km/hr

When come downstream

x + 4 km/hr

• Time to go downstream = 12 hr

• Time to come upstream = 18 hr

Now,

• S = D/T

• S is the Speed

• D is the Distance

• T is the Time

Downstream = s/12 = (x + 4)

Upstream = s/18 = (x - 4)

s/18 × 12/s = (x + 4)/(x - 4)

18/12 = (x + 4)/(x - 4)

9/6 = (x + 4)/(x - 4)

6(x + 4) = 9(x - 4)

6x + 24 = 9x - 36

9x - 6x = 36 + 24

3x = 60

x = 20

$\underline{\boxed{ \sf \: Speed = 20 km/h}}$