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3 years ago

Many drove 45 miles in 0.75 hours. What was the average rate he drove in miles per hour

Mathematics

2 answers:

Digiron [165]3 years ago

8 0

Answer:

Average rate is 60 miles per hour

Step-by-step explanation:

Speed is a average rate at which someone or something covering the distance in a unit time. Speed is the average rate of movement.

As per given data

Distance = 45 miles

Time Taken = 0.75 hours

As we know , the formula of speed is

Speed = Distance / Time

Speed = 45 miles / 0.75 hours

Speed = 60 miles per hour

Cerrena [4.2K]3 years ago

5 0

Speed= distance / time = 45 / 0.75 = 60 miles per hour

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Area of a triangle with points at (-9,5), (6,10), and (2,-10)

Ann [662]

First we are going to draw the triangle using the given coordinates.
Next, we are going to use the distance formula to find the sides of our triangle.
Distance formula: $d= \sqrt{(x_{2}-x_{1})^2+(y_{2}-y_{1})^2}$

Distance from point A to point B:
$d_{AB}= \sqrt{[6-(-9)]^2+(10-5)^2}$
$d_{AB}= \sqrt{(6+9)^2+(10-5)^2}$
$d_{AB}= \sqrt{(15)^2+(5)^2}$
$d_{AB}= \sqrt{225+25}$
$d_{AB}= \sqrt{250}$
$d_{AB}=15.81$

Distance from point A to point C:
$d_{AC}= \sqrt{[2-(-9)]^2+(-10-5)^2}$
$d_{AC}= \sqrt{(2+9)^2+(-10-5)^2}$
$d_{AC}= \sqrt{11^2+(-15)^2}$
$d_{AC}= \sqrt{121+225}$
$d_{AC}= \sqrt{346}$
$d_{AC}= 18.60$

Distance from point B from point C
$d_{BC}= \sqrt{(2-6)^2+(-10-10)^2}$
$d_{BC}= \sqrt{(-4)^2+(-20)^2}$
$d_{BC}= \sqrt{16+400}$
$d_{BC}= \sqrt{416}$
$d_{BC}=20.40$

Now, we are going to find the semi-perimeter of our triangle using the semi-perimeter formula:
$s= \frac{AB+AC+BC}{2}$
$s= \frac{15.81+18.60+20.40}{2}$
$s= \frac{54.81}{2}$
$s=27.41$

Finally, to find the area of our triangle, we are going to use Heron's formula:
$A= \sqrt{s(s-AB)(s-AC)(s-BC)}$
$A=\sqrt{27.41(27.41-15.81)(27.41-18.60)(27.41-20.40)}$
$A= \sqrt{27.41(11.6)(8.81)(7.01)}$
$A=140.13$

We can conclude that the perimeter of our triangle is 140.13 square units.

3 0

2 years ago

Situation:A researcher in North America discoversa fossile that contains 65% of its originalamount of C-14..-ktN=NoeNo inital am

zheka24 [161]

SOLUTION

We have been given the equation of the decay as

$\begin{gathered} N=N_0e^{-kt} \\ where\text{ } \\ N_0=initial\text{ amount of C-14 at time t} \\ N=amount\text{ of C-14 at time t = 65\% of N}_0=0.65N_0 \\ k=0.0001 \\ t=time\text{ in years = ?} \end{gathered}$

So we are looking for the time

Plugging the values into the equation, we have

$\begin{gathered} N=N_0e^{-kt} \\ 0.65N_0=N_0e^{-0.0001t} \\ e^{-0.0001t}=\frac{0.65N_0}{N_0} \\ e^{-0.0001t}=0.65 \end{gathered}$

Taking Ln of both sides, we have

$\begin{gathered} ln(e^{-0.000t})=ln(0.65) \\ -0.0001t=ln(0.65) \\ t=\frac{ln(0.65)}{-0.0001} \\ t=4307.82916 \end{gathered}$

Hence the answer is 4308 to the nearest year

8 0

9 months ago

An employee working in a machine shop is exposed to three different sources which emit noises at 81 dB, 91 dB, and 88 dB. What i

leonid [27]

Hello,
Please, see the attached file.
Thanks.

5 0

3 years ago

The line y+2x=b is perpendicular to a line that passes through the origin. If the two lines intersect at one point (k+2,2k), wha

Grace [21]

Answer:

The line y+2x=b is perpendicular to a line that passes through the origin. If the two lines intersect at the point (k+2,2k)

Step-by-step explanation:

that should be right

6 0

2 years ago

Please help :(<br> [math]

sergij07 [2.7K]

Hey!

------------------------------------------------

First Equation:

2x + 3 = -7

2x + 3 - 3 = -7 - 3 (Subtract 7 to both sides)

2x = -10

2x/2 = -10/2 (Divide 2 to both sides)

x = -5

------------------------------------------------

Second Equation:

4.5x - 7 = 20

4.5x + (-7) + 7 = 20 + 7 (Add 7 to both sides)

4.5x = 27

4.5x/4.5 = 27/4.5 (Divide 4.5 to both sides)

x = 6

------------------------------------------------

Third Equation:

-3x + 7 = 28

-3x + 7 - 7 = 28 - 7 (Subtract 7 to both sides)

-3x/-3 = 21/-3 (Divide -3 to both sides)

x = -7

------------------------------------------------

Answers:

2x + 3 = -7 → x = -5

4.5x - 7 = 20 → x = 6

-3x + 7 = 28 → x = -7

------------------------------------------------

Hope This Helped! Good Luck!

8 0

3 years ago