N x 1 = n is what property?

The total surface area of this cuboid is 112cm^2. Find the value of x.

Oxana [17]

Answer:

The value of x is 3

Step-by-step explanation:

Let us study the face of the cuboind

∵ The cuboid has 6 rectangular faces

∵ Each opposite faces area equal in areas

∴ 2 faces of dimensions 10 cm and 2 cm

∴ 2 faces of dimensions 10 cm and x cm

∴ 2 faces of dimensions 2 cm and x cm

∵ The total surface area of the cuboid is the sum of the areas of the 6 faces

∵ The area of the rectangle = length × width

∴ The total surface area = 2(10 × 2) + 2(10 × x) + 2(2 × x)

∴ The total surface area = 2(20) + 2(10x) + 2(2x)

∴ The total surface area = 40 + 20x + 4x

→ Add the like terms 20x and 4x

∴ The total surface area = 40 + 24x

∵ The total surface area of this cuboid is 112 cm²

→ Equate the two sides of the total surface area

∴ 40 + 24x = 112

→ Subtract 40 from both sides

∵ 40 - 40 + 24x = 112 - 40

∴ 24x = 72

→ Divide both sides by 24

∴ x = 3

∴ The value of x is 3

7 0

2 years ago

Read 2 more answers

Scores on a final exam taken by 1200 students have a bell shaped distribution with mean=72 and standard deviation=9

SVETLANKA909090 [29]

Answer:

a. 72

b. 816

c. 570

d. 30

Step-by-step explanation:

Given the graph is a bell - shaped curve. So, we understand that this is a normal distribution and that the bell - shaped curve is a symmetric curve.

Please refer the figure for a better understanding.

a. In a normal distribution, Mean = Median = Mode

Therefore, Median = Mean = 72

b. We have to know that 68% of the values are within the first standard deviation of the mean.

i.e., 68% values are between Mean $\pm$ Standard Deviation (SD).

Scores between 63 and 81 :

Note that 72 - 9 = 63 and

72 + 9 = 81

This implies scores between 63 and 81 constitute 68% of the values, 34% each, since the curve is symmetric.

Now, Scores between 63 and 81 = $\frac{68}{100} \times 1200$

= 68 X 12 = 816.

That means 816 students have scored between 63 and 81.

c. We have to know that 95% of the values lie between second Standard Deviation of the mean.

i.e., 95% values are between Mean $\pm$ 2(SD).

Note that 90 = 72 + 2(9) = 72 + 18

Also, 54 = 63 - 18.

Scores between 54 and 90 totally constitute 95% of the values. So, Scores between 72 and 90 should amount to $\frac{95}{2} \%$ of the values.

Therefore, Scores between 72 and 90 = $\frac{95}{2(100)} \times 1200 = \frac{95}{200} \times 1200$

$\implies 95 \times 12$ = 570.

That is a total of 570 students scored between 72 and 90.

d. We have to know that 5 % of the values lie on the thirst standard Deviation of the mean.

In this case, 5 % of the values lie between below 54 and above 90.

Since, we are asked to find scores below 54. It should be 2.5% of the values.

So, Scores below 54 = $\frac{2.5}{100} \times 1200$

= 2.5 X 12 = 30.

That is, 30 students have scored below 54.

8 0

3 years ago

The volume of the pyramid shown in the figure is cubic centimeters. If the slant height of the pyramid increases by 4 centimeter

Nostrana [21]

Answer:

Part a) The volume of the original pyramid is $15\ cm^{3}$

Part b) The volume of the pyramid increases by $6\ cm^{3}$

Step-by-step explanation:

<u><em>The complete question is</em></u>

Part 1) The volume of the pyramid shown in the figure is 9,15,21, or 63 cubic centimeters?. Part 2) If the slant height of the pyramid increases by 4 centimeters and its height increases by 2 centimeters, the volume of the pyramid increases by 6,9,12 or 21 cubic centimeters?

we know that

The volume of the pyramid is equal to

$V=\frac{1}{3}Bh$

where

B is the area of the base

h is the height of pyramid

see the attached figure to better understand the problem

Step 1

Find the volume of the original pyramid

the area of the base B is equal to

$B=3^{2}=9\ cm^{2}\\h=5\ cm$

substitute

$V=\frac{1}{3}(9)(5)=15\ cm^{3}$

Step 2

Find the volume of the new pyramid

$B=9\ cm^{2}$ -------> the area of the base is the same

$h=5+2=7\ cm$ ------> the height increase by

substitute

$V=\frac{1}{3}(9)(7)=21\ cm^{3}$

Subtract the original volume from the new volume

$21\ cm^{3}-15\ cm^{3}=6\ cm^{3}$

5 0

3 years ago

A cylindrical grain bin has a radius of 9 feet and a height of 30 feet. What is the surface area of the bin

vivado [14]

1696.46 square feet
2x(9x9xpi) for the circular ends
9x2xpi for the diameter of the circle the multiply by 30 for the surface area of the sides
Add together to get 1696.46 square feet

6 0

3 years ago

What is the slope of this line?

V125BC [204]

The slope is -3.

rise = 3
run = -1

3
------- = -3
-1

4 0

3 years ago