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pshichka [43]
2 years ago
11

If a boat goes down stream 72 milesind upstream 60 miles in 6 hours, the rate of the river and the rate of the boat in still wat

er respectively are
Mathematics
1 answer:
andre [41]2 years ago
3 0

Answer:

Speed of boat in still water = 11 miles per hour.

Step-by-step explanation:

Speed = distance / time

or

Distance= Speed * time

Let s be speed of the boat upstream and r be the speed of the river.

Then

Upstream speed=  s- r = 60/6= 10 miles per hour

Downstream speed= s+r= 72/6= 12 miles per hour

Therefore

s-r= 10--------- equation A

s+r= 12--------- equation B

Adding equation A and Eq. b

s-r= 10--------- equation A

<u>s+r= 12--------- equation B     </u>

<u>2s    = 22                             </u>

<u />

or

s= 22/2= 11 miles per hour.

Speed of boat in still water = 11 miles per hour.

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1.- Maria compro $750 en mercancia, por pajar en efectivo le hacen un descuento del 15%, ¿cuánto pago Maria con el descuento?
miss Akunina [59]

Answer:

$637.5

Step-by-step explanation:

Given data

Cost of  merchandise= $750

Discount= 15%

Let us find the amount of the discount

=15/100*750

=0.15*750

=$112.5

Hence the amount paid will be

=750-112.5

=$637.5

5 0
2 years ago
Rachel has 30 pounds of a mixture of candy that sells for $1.00/lb. If lollipops sell for $0.95/lb and caramel candies sell for
Lina20 [59]

Answer:

Twenty Pounds

Step-by-step explanation:

Equation #1:

30lbs x Mix Price = (Lollipop Lbs  x 0.95)  + (Caramel Lbs X 1.10)

Equation #2:

Lollipops Lbs + Caramel Lbs = 30 Lbs

<em>Rearrange expressions to solve for different variables</em>

EQ1:   Caramel Lbs = (30 - .95 Lollipop Lbs)/ 1.10      NOTE: (mix price = 1.00)

EQ2:  Lollipop Lbs = 30 - Caramel Lbs

<em>Substitute formula 1 into formula 2</em>

Lollipop Lbs = 30 - [(30 - .95 Lollipop Lbs)/1.10]

<em>Distribute divisor</em>

Lollipop Lbs  = 30 - 27.2727 + .8636 Lollipop Lbs

<em>Collect terms</em>

Lollipop Lbs  =  2.7273 + .8636 Lollipop Lbs

<em>Remove .8336 Lollipops from both sides of the equation</em>

.1364 Lollipop Lbs = 2.7273

<em>Divide both sides by .1364  </em> (Answer is  19.9949 which rounds to 20)

Lollipop Lbs =  20

PROOF:

30 = (20 x 0.95) + (10 x 1.10)

30 = 19 + 11

30 = 30   TRUE!


6 0
2 years ago
2. Karen was cutting out some fabric
solmaris [256]

Answer:

42 cm .

l hope it maybe helps

6 0
3 years ago
Read 2 more answers
Which expression is a fourth root of -1+isqrt3?
aleksklad [387]

Answer:

Step-by-step explanation:

\sf n^{th} roots of a complex number is given by DeMoivre's formula.

   \sf \boxed{\bf r^{\frac{1}{n}}\left[Cos \dfrac{\theta + 2\pi k}{n}+i \ Sin \ \dfrac{\theta+2\pi k}{n}\right]}

Here, k lies between 0 and (n -1) ; n is the exponent.

\sf -1 + i\sqrt{3}

a = -1 and b = √3

\sf \boxed{r=\sqrt{a^2+b^2}} \ and \ \boxed{\theta = Tan^{-1} \ \dfrac{b}{a}}

\sf r = \sqrt{(-1)^2 + 3^2}\\\\ = \sqrt{1+9}\\\\=\sqrt{10}

                   \sf \theta = tan^{-1} \ \dfrac{\sqrt{3}}{-1}\\\\ = tan^{-1} \ (-\sqrt{3})

                   \sf = \dfrac{-\pi }{3}

n = 4

For k = 0,

          \sf z = \sqrt[4]{10}\left[Cos \ \dfrac{\dfrac{-\pi}{3} +0}{4}+iSin  \ \dfrac{\dfrac{-\pi}{3}+0}{4}\right] \\\\\\z= \sqrt[4]{10} \left[Cos \ \dfrac{ -\pi  }{12}+iSin  \ \dfrac{-\pi}{12}\right]\\\\\\z = \sqrt[4]{10}\left[-Cos \ \dfrac{\pi}{12}-i \ Sin \ \dfrac{\pi}{12}\right]

For k =1,

         \sf z = \sqrt[4]{10}\left[Cos \ \dfrac{5\pi}{12}+i \ Sin \ \dfrac{5\pi}{12}\right]

For k =2,

       z = \sqrt[4]{10}\left[Cos \ \dfrac{11\pi}{12}+i \ Sin \ \dfrac{11\pi}{12}\right]

For k = 3,

      \sf z = \sqrt[4]{10}\left[Cos \ \dfrac{17\pi}{12}+i \ Sin \ \dfrac{17\pi}{12}\right]

For k = 4,

      \sf z =\sqrt[4]{10}\left[Cos \ \dfrac{23\pi}{12}+i \ Sin \ \dfrac{23\pi}{12}\right]

4 0
1 year ago
The width of a rectangle is 4 inches (in) and the area of the rectangle is 32 in2? Which of the following represents the length
miv72 [106K]

Answer:

A. 8

Step-by-step explanation:

32 divided by 4 = 8

5 0
3 years ago
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