Please solve.................A man is rowing a boat at a uniform speed. The speed with the current is 2km/h?

Question

A man is rowing a boat at a uniform speed. The speed with the current is 2km/h greater than against it. He takes a total of 4 hours to row with the current from A to B and then against it from B to A. If the distance between A and B is 15 km, find the speed of the boat from A to B (i.e. with the curent)

(use a variable to represtn the unknown quantity, form an equation, solve the equation..............)

Answer 1

let

x+ 2 = with the current

x - 2 = against the current

4 = total hours with and against the current

15 = Distance Traveled

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With the current

4(x + 2) = 15

4x + 8 = 15

4x + 8 - 8 = 15 - 8

4x = 7

4x/4 = 7/4

x = 1 3/4 hours

x = 1.75

X = 1 Hour and 45 minutes

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The rate of the boat with the current

d = rt

d/t = r

15/1.75 = 8.5791428571 km/h

8.57 km/h

The answer is 8.57 km/h with current

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Against the current

4(x - 2) = 15

4x - 8 = 15

4x - 8 + 8 = 15 + 8

4x = 13

4x/4 = 23/4

x = 5 3/4

x = 5.75 hours

x = 5 Hours 45 minutes

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Rate of the boat against the current

d = rt

d/t = r

15/5.75 = 2.608695652 km/h

2.61 km/h

The answer is 2.61 km/h against the current

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Answer 2

V= velocity
S= distance
T= time

V=S/T

V=15/4
V=5.75km/h
Add 2 to the answer because the boat is rowing with the current

V=5.75+2
V from A to B= 7.75km/h.

Answer 3

His speed with the current is: 8.63 km/h (rounded off)

This is the type of question a lot of people make a mistake on.

Let V be the speed the man rows, and c the speed of the current.
You need to determine V+c which is his speed with the current.
You are given the (V+c)-(V-c) = 2c = 2km/h. So c= 1 km/h
So you need to determine V.

d=v*t (distance = velocity x time)

And: t = d/v

The time taken for the trip from A to B = 15km/(V+c)
The time taken for the trip from B to A = 15km/(V-c)

The time for the round trip is 4 hrs.

So 4hr = 15km/(V+c) + 15km/(V-c)

Dropping units for now, we have:

4 = 15[1/(V+c) + 1/(V-c)]

4 = 15[(V-c+V+c)/(V+c)(V-c)]

4 = 15[2V / (V^2-c^2)]

c=1, so

4 = 15* 2V / (V^2 -1)

2=15V / (V^2 -1)

2V^2 -15V-2 =0

Using the quadratic formula, we have:

V = 7.631 km/h

So his speed with the current = V+c = 8.631 km/h
his speed against the current = V-c = 6.631 km/h

The time taken for the trip from A to B = 15/8.63 = 1.74 hrs =
1hr 44 min 24 sec
The time from B to A = 2hr 15min 36 sec

Answer 4

7.2kph my boyfriends says

p.s. give him a hard one "question that is"