Ask question

Ask question

All categories

3 years ago

5

The current of a river is 4 miles per hour. A boat travels to a point 30 miles upstream and back in 4 hours. What is the speed o

f the boat in still water?

1 answer:

Maurinko [17]3 years ago

7 0

16 mph is the answer I found after doing the work

You might be interested in

Find the ages of the people and tree

Harlamova29_29 [7]

Answer:

1. Callum = 2; Eilidh = 17; Caitlin's =22.

2. Ewan = 44; tree = 308.

Explanation:

Q1. Callum, Eilidh, and Caitlin

Let x = Callum's age

y = Eilidh's age

z = Caitlin's age

We have three conditions.

(1) x = y - 5

(2) z = y + 15

(3) x + y + z = 31

Step 1. Eliminate one of the variables in two of the equations

Subtract (1) from (2): z - x = 20

Rearrange: (4) -x + z = 20

Solve (2) for y: (5) y = z - 15

Substitute into (3): x + z - 15 + z = 31

(6) x + 2z = 46

Step 2. Set up two new equations in two variables

(5) -x + z = 20

(6) x + 2z = 46

Add (5) and (6): 3z = 66

Divide each side by 2: z = 22

Step 3. Substitute z into (5)

-x + 22 = 20

x = 2

Step 4. Substitute x into (1)

2 = y - 5

Add 5 to each side y = 7

Callum's age is 2; Eilidh's age is 7; Caitlin's age is 22.

Q2. Ewan and the tree

Let x = Ewan's age

y = tree's age

We have two conditions.

(1) y = 7x

(2) x + y = 352

Rearrange (1) (3) -7x + y = 0

(2) x + y = 352

Subtract (3) from (2) 8x = 352

Divide each side by 8 x = 44

Substitute y into (1) y = 7 × 44

y = 308

Ewan's age is 44; the tree's age is 308.

5 0

3 years ago

What is 7.5 as a decimal?

OlgaM077 [116]

7.5?????????? hope you get this right

8 0

3 years ago

What is the value of x in the equation 3x-1/9y=18, when y=27?

natulia [17]

Hi Vanessa

3x -1/9 (27) =18

3x - 27/9 =18

3x- 3 =18

Add 3 to both sides

3x-3+3=18+3

3x=21

Divide both sides by 3

3x/3= 21/3

x= 7

The value of x is 7

Now let's check if my answer is correct

To check it we gonna replace x by 7 and 27 for y

(3)(7) -1/9 (27) = 18

21 -1/9 (27)=18

21- 27/9 = 18

21- 3 = 18

18 = 18

The answer is good and I hope its help:0

5 0

3 years ago

If x is Equal to 7, what is 7 divided by 3 and round it up

VikaD [51]

Answer:

2.3 or 2

Step-by-step explanation:

7 0

3 years ago

Suppose you pay a dollar to roll two dice. if you roll 5 or a 6 you Get your dollar back +2 more just like it the goal will be t

LiRa [457]

Answer:

(a)$67

(b)You are expected to win 56 Times

(c)You are expected to lose 44 Times

Step-by-step explanation:

The sample space for the event of rolling two dice is presented below

$(1,1), (2,1), (3,1), (4,1), (5,1), (6,1)\\(1,2), (2,2), (3,2), (4,2), (5,2), (6,2)\\(1,3), (2,3), (3,3), (4,3), (5,3), (6,3)\\(1,4), (2,4), (3,4), (4,4), (5,4), (6,4)\\(1,5), (2,5), (3,5), (4,5), (5,5), (6,5)\\(1,6), (2,6), (3,6), (4,6), (5,6), (6,6)$

Total number of outcomes =36

The event of rolling a 5 or a 6 are:

$(5,1), (6,1)\\ (5,2), (6,2)\\( (5,3), (6,3)\\ (5,4), (6,4)\\(1,5), (2,5), (3,5), (4,5), (5,5), (6,5)\\(1,6), (2,6), (3,6), (4,6), (5,6), (6,6)$

Number of outcomes =20

Therefore:

P(rolling a 5 or a 6) $=\dfrac{20}{36}$

The probability distribution of this event is given as follows.

$\left|\begin{array}{c|c|c}$Amount Won(x)&-\$1&\$2\\&\\P(x)&\dfrac{16}{36}&\dfrac{20}{36}\end{array}\right|$

First, we determine the expected Value of this event.

Expected Value

$=(-\$1\times \frac{16}{36})+ (\$2\times \frac{20}{36})\\=\$0.67$

Therefore, if the game is played 100 times,

Expected Profit =$0.67 X 100 =$67

If you play the game 100 times, you can expect to win $67.

(b)

Probability of Winning $=\dfrac{20}{36}$

If the game is played 100 times

Number of times expected to win

$=\dfrac{20}{36} \times 100\\=56$ times$

Therefore, number of times expected to loose

= 100-56

=44 times

8 0

3 years ago