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postnew [5]
3 years ago
7

the excursion boat on the river takes 2 1/2 hours to make the trip to a point 12 miles up stream and to return. If the rate at w

hich the boat travels in still water is 5 times the rate of the river current, what is the rate of the current?
Mathematics
1 answer:
MissTica3 years ago
4 0
Let V, be the rate in still water and let C = rate river current
If the boat is going :
upstream, its rate is V-C and if going 
downstream, its rate is V+C,
But V = 5C, then
Upstream Rate: 5C - C = 4 C
Downstream rate: 5C+C = 6C

Time = distance/Rate,  (or time = distance/speed) , then:
Upstream time 12/4C and
Downstream time: 12/.6C

Upstream time +downstream time:= 2h30 ' then:

12/4C + 12/.6C = 2.5 hours
3/C + 2/C = 5/2 (2.5 h = 5/2)
Reduce to same denominator :
 5C = 10 and Rate of the current = 2 mi/h

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Semicircles
Studentka2010 [4]

Answer:

The area of the shaded portion of the figure is 9.1\ cm^2

Step-by-step explanation:

see the attached figure to better understand the problem

we know that

The shaded area is equal to the area of the square less the area not shaded.

There are 4 "not shaded" regions.

step 1

Find the area of square ABCD

The area of square is equal to

A=b^2

where

b is the length side of the square

we have

b=4\ cm

substitute

A=4^2=16\ cm^2

step 2

We can find the area of 2 "not shaded" regions by calculating the area of the square less two semi-circles (one circle):

The area of circle is equal to

A=\pi r^{2}

The diameter of the circle is equal to the length side of the square

so

r=\frac{b}{2}=\frac{4}{2}=2\ cm ---> radius is half the diameter

substitute

A=\pi (2)^{2}

A=4\pi\ cm^2

Therefore, the area of 2 "not-shaded" regions is:

A=(16-4\pi) \ cm^2

and the area of 4 "not-shaded" regions is:

A=2(16-4\pi)=(32-8\pi)\ cm^2

step 3

Find the area of the shaded region

Remember that the area of the shaded region is the area of the square less 4 "not shaded" regions:

so

A=16-(32-8\pi)=(8\pi-16)\ cm^2  

---> exact value

assume

\pi =3.14

substitute

A=(8(3.14)-16)=9.1\ cm^2

8 0
3 years ago
Suppose you are doing a puzzle. After 10 minutes, you have 275 pieces placed, and after 22 minutes, you have 395 pieces placed.
LenKa [72]

Answer:

600 pieces

Step-by-step explanation:

pieces/ time(min) = (395-275) / (22-10) = 120/ 12 = 10

10= x (pieces) / 60(min) => x = 60×10 => x = 600 pieces

4 0
3 years ago
Find the value of X.
ch4aika [34]

Answer:

x= 60

Step-by-step explanation:

if y is the other missing side

y^2 = 64^2 + 48^2

y^2 = 4,096 + 2,304

y^2 = 6,400

100^2 = x^2 +y^2

x^2 = 10,000 - 6,400

x^2 = 3,600

x = 60

6 0
3 years ago
Please help meee im being timed on thisss
sattari [20]

Answer:

y=0.25x

We can think of k as an unknown number.

8×_=2.00

12×_=3.00

20×_=5.00

If we divide 2 with 8 we are left with 0.25.

It's the same for the other numbers so we know the constant is 0.25.

When we use the formula y=0.25x with the numbers above, it is correct.

8×0.25=2.00

12×0.25=3.00

20×0.25=5.00

4 0
3 years ago
Who can answer the 3x+2y=-6 for the intercepts and to graph it ?? I'm so lost
ELEN [110]
Y-intercept: 3
x-intercept: 2

put (0,3) and (2,0) as points on the graph
7 0
3 years ago
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