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Ede4ka [16]
3 years ago
7

Answer these please!!!!

Mathematics
1 answer:
mel-nik [20]3 years ago
6 0

Answer:

2/3

Step-by-step explanation:

i hope this helps but um... 2/1÷2/3=2/3

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For the amusement of the guests, some hotels have elevators on the outside of the building. One such hotel is 400 feet high. You
Mariana [72]

9514 1404 393

Answer:

  a.  h(t) = -20t +400

  b.  θ(t) = arctan(2 -2/15t); dθ/dt = -30/(1125 -120t +4t^2)

  c.  15 seconds; 100 ft

Step-by-step explanation:

a. The initial height of the elevator is 400 ft. The rate of change of height is -20 ft/s, so the height equation can be ...

  h(t) = -20t +400

__

b. The tangent of the angle above the line of sight is "opposite"/"adjacent":

  tan(θ) = (h(t) -100)/(150) = -2/15t +2

  θ(t) = arctan(2 -2/15t) . . . . radians

The derivative of the angle function is ...

  dθ/dt = 1/(1+(2 -2/15t)^2)(-2/15)

  dθ/dt = -30/(1125 -120t +4t^2)

__

c. The value of dθ/dt will have a peak where the denominator has a minimum, at t = -(-120)/2(4)) = 15. (The quadratic vertex coordinate is t=-b/(2a).)

The elevator appears to be moving fastest at t=15 seconds.

The height at that time is ...

  h(15) = 400 -20(15) = 100

The elevator appears to be moving fastest when it is at eye level, 100 ft above the ground.

5 0
3 years ago
Someone please help me it’s urgent!!! I promise to mark brainlest!
evablogger [386]
The answer to the question is c

6 0
4 years ago
A car travels 30 1/5 miles in 2/3 of an hour. Whwt is the average speed, in miles per hour, of the car​
LiRa [457]

Answer:

45 3/10 mph

Step-by-step explanation:

30 1/5 /2 = 15 1/10

15 1/10 x 3 = 45 3/10 mph

8 0
3 years ago
A semi-circle sits on top of a rectangle to form the figure below. Find its area and perimeter. Use 3.14 for
zmey [24]

Answer:

Perimeter: 18.28

Area: 22.28

Step-by-step explanation:

1. Approach

An easy method that can be used to solve the given problem is the partition the given figure into two smaller figures. One can divide this figure into a square and a semi-circle. After doing so, one can find the area of the semi-circle and the area of the square. Finally, one can add the two area together to find the final total area. To find the perimeter of the figure, one can add the lengths of three of the sides of the square and then one can add half of the circumference of the circle to the result. The final value will be the perimeter of the entire figure.

2. Find the circumference of the semi-circle

The circumference of a circle is the two-dimensional distance around the outer edge of a circle, in essence the length of the arc around a circle. The formula to find the circumference of a circle is as follows,

C = 2(pi)r

Since a semi-circle is half of a circle, the formula to find its circumference is the following,

C = (pi)

Where (pi) is the numerical value (3.1415) and (r) is the radius of the circle. By its definition, the radius of a circle is the distance from a point on the circle to the center of the circle. This value will always be half of the diameter, that is the distance from one end of the circle to the other, passing through the center of the circle. The radius of a circle is always half of the diameter, thus the radius of this semi-circle is (2). Substitute this into the formula and solve for the circumference;

C = (pi)r

C = (pi)2

C ~ 6.28

3. Find the area of the semi-circle

The formula to find the area of a circle is as follows,

A = (\pi)(r^2)

As explained earlier, a semi-circle is half of a circle, therefore, divide this formula by (2) to find the formula for the area of a semi-circle

A = ((pi)r^2)/(2)

The radius of this circle is (2), substitute this into the formula and solve for the area of a semi-circle;

A = ((pi)r^2)/(2)

A = ((pi)(2^2))/(2)

A = (pi)2

A = 6.28

4. Find the area and perimeter of the square,

The perimeter of a figure is the two-dimensional distance around the figure. Since the semi-circle is attached to one of the sides of a square, one only needs to add three sides of the square to find the perimeter of the square;

P = 4+4+4

P = 12

The area of a square can be found by multiplying the length by the width of the square.

A = l*w

Substitute,

A = 4*4

A=16

5. Find the area and the perimeter of the figure,

To find the perimeter of the figure, add the value of the circumference to the vlalue of the perimeter of the square;

A = C+P

A = 6.28+12

A = 18.28

To find the area of the figure, add the value of the area of the circle to the area of the square;

A = 6.28+16

A = 22.28

3 0
3 years ago
A random sample of house sizes in major city has a sample mean of x¯=1204.9 sq ft and sample standard deviation of s=124.6 sq ft
ki77a [65]

Answer:

About 95% of house sizes that lie between 955.7 and 1454.1 sq ft .

Step-by-step explanation:

According to the empirical rule  about 68% of the data is within one standard deviation of the mean; about 95% of the data is within two standard deviations of the mean ; about 99.7% of the data is within three standard deviations of the mean.

We have given:

Sample mean : x¯=1204.9 sq ft

Standard deviation: s=124.6 sq ft

To find the percentage of house sizes that lie between 955.7 and 1454.1 sqft.

We can write it as

955.7= 1204.9 - 249.2 = 1204.9 - 2(124.6)

and 1454.1  = 1204.9 + 249.2 = 1204.9 + 2(124.6)

Thus, 955.7 is 2 standard deviations left from the means and 1454.1 is 2 deviations right from the mean.

Then by empirical rule , about 95% of house sizes that lie between 955.7 and 1454.1 sq ft .

8 0
4 years ago
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