1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Snezhnost [94]
3 years ago
15

Jane took 20 min to drive her boat upstream to​ water-ski at her favorite spot. Coming back later in the​ day at the same boat​

speed took her 10 min. If the current in that part of the river is 4 km per​ hr, what was her boat speed in still​ water?
Mathematics
2 answers:
nlexa [21]3 years ago
7 0

Answer:

12 km/hour

Step-by-step explanation:

Given information: The current in that part of the river is 4 km per​ hr.

Speed of current = 4 km per hour

Let x be the speed of boat in still​ water.

Speed of boat in upstream = x-4 km per hour

Speed of boat in downstream = x+4 km per hour

Assume that the distance between Jane's initial position and Jane's favorite spot is D.

Jane took 20 min to drive her boat upstream to​ water-ski at her favorite spot.

Distance=Speed\times Time

For upstream,

Distance=(x-4)\times 20

Distance=20x-80            .... (1)

For downstream,

Distance=(x+4)\times 10  

Distance=10x+40           ..... (2)

Equate (1) and (2) we get

20x-80=10x+40

Isolate variable terms.

20x-10x=80+40

10x=120

Divide both sides by 10.

x=12

The value of x is 12. Therefore, the speed of boat in still water is 12 km/hour.

Bingel [31]3 years ago
5 0

(x-5)*20 = d
coming downstream:
(x+5)*15 = d
since both equations equal d, then they are equal to each other, so:
(x-5)*20 = (x+5)*15
expanding, this becomes:
20*x - 100 = 15*x + 75
subtract 15*x from both sides and add 100 to both sides to get:
20*x - 15*x = 75 + 100
which becomes:
5*x = 175


divide both sides by 5 to get:
x = 35 miles per hour
this means that the boat's speed is 35 miles per hour.
---
to prove this is correct, substitute in the original equation of:
(x-5)*20 = (x+5)*15
which becomes:
(35-5)*20 = (35+5)*15
which becomes:
30*20 = 40*15
divide both sides by 15 to get:
30/15*20 = 40
which becomes:
2*20 = 40
which is true so the values for the boat speed are good.
---
your answer
You might be interested in
The average number of employees that call in sick for the day over the course of a year is 25.
Georgia [21]

Answer:

24

Step-by-step explanation:

add all the numbers up and then divide that number by the amount of numbers there are

3 0
3 years ago
Please help asap pleaseeeew
wel

Answer:

6.

Step-by-step explanation:

1) OA=d/2=20/2=10;

2) AB=AC/2=16/2=8;

3) \ OB=\sqrt{OA^2-AB^2} =6.

3 0
2 years ago
The figure shown is a rectangle. If you draw a new rectangle in which the dimensions are doubled, what is the relationship betwe
stellarik [79]

Answer:

Step-by-step explanation:

Givens

L = 5

w = 3

Formula

Area = L*w

Solution

Area = 3 * 5

Area = 15

Now double both the width and the Length.

New Length = 2*5 = 10

New Width = 2 * 3 = 6

Area = New Length * New Width

Area = 10 * 6

Area = 60

Answer (look at the choices)

The old rectangle has an area of 15. The new Rectangle has an area of 60. If you double 15, do you get 60. No, so the answer is not A

The new rectangle is 60. If you halve it, do you get 15. No so the answer is Not B

C is the answer

D is you multiply 8 * 15, do you get 60? No so the answer is not D

8 0
2 years ago
Match each inequality to the number line that represents its solution
vlada-n [284]

the first one that is x-99....... goes to the second answer box

the second that is x-51......... goes to the first answer box

the third that is 150+x......... goes to the fourth answer box

the fourth that is 69-x......... goes to the third answer box

3 0
3 years ago
Read 2 more answers
Explain one thing you need to be careful with when writing a proportion.
ehidna [41]

For this case, we have that by definition, the proportions can be expressed in different ways. Example, if we have a dog and three cats:

75%: It's percentage

0.75: In decimal (75% are cats)

\frac {3} {4}: In fraction. (There are \frac {3} {4} of cats)

3: 1: Using ":" to separate sample values. (For every three cats there is a dog)

Care should be taken with the proportions, always multiplying the numbers in the proportion by the same value.

Example:3: 1 = 3 * 2: 1 * 2 = 6: 2

Answer:

Care should be taken with the proportions, always multiplying the numbers in the proportion by the same value.

7 0
3 years ago
Other questions:
  • Which line is parallel to the line 8x + 2y = 12?<br> 19
    13·1 answer
  • How do i change standard form equations back into slope intercept form?
    10·1 answer
  • I would hate to ask another question but Avery had $25.63 in her wallet. If she bought lunch with 7 1/4 dollars from her wallet,
    12·2 answers
  • Pls help me :D .....
    13·1 answer
  • Trigonometry help ! tysm
    10·1 answer
  • Carrie saved money to spend while on a one-month vacation to Europe. On day 8, she had $2,400 remaining. On day 16, she had $1,6
    10·2 answers
  • 'find the equation of the line shown':
    11·1 answer
  • 3 + 4n + n = 2n + 15
    15·2 answers
  • I need help plz!!!!<br> I need help plz!!!
    12·1 answer
  • Find the mode of the following data: 5, 0, 5, 4, 12, 2, 14
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!