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nata0808 [166]
3 years ago
10

A dump truck driver is delivering loads of sand for making sandbags to protect homes from flooding. Each load contains 12 m3 of

sand and piles up into the shape of a cone as shown below. It is estimated that the pile will be large enough when it is 17m across and 9m high. How many truck loads of sand are needed?
Mathematics
1 answer:
DaniilM [7]3 years ago
5 0

Answer:

  57

Step-by-step explanation:

The volume of a cone is given by the formula ...

  V = (1/3)πr²h

For a pile with a radius of 8.5 m and a height of 9 m, the volume is ...

  V = (1/3)π(8.5 m)²(9 m) = 216.75π m³ ≈ 680.94 m³

Then the number of truckloads required to create that size pile will be ...

  (680.94 m³)/(12 m³/truck) = 56.745 trucks

Even a partial truck load entails another trip, so ...

  57 truck loads of sand are needed.

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A fishing lodge wants to build a new boat ramp. The slope of the ramp must be 8° to the horizontal. The total height of the bank
Likurg_2 [28]

Answer:

The length of the sloping section of the ramp is 20.12 m

Step-by-step explanation:

Given;

the total height of the bank, h = 2.8 m

The slope of the ramp must be 8° to the horizontal, i.e, θ = 8°

Let the length of the sloping section = L

let the horizontal distance between the height of the bank and sloping section = b

Thus, h, L and b forms three sides of a right angled-triangle, with L as the hypotenuse side, h  (height of the triangle) as the opposite side and b  (base of the triangle) as the adjacent side.

We determine L by applying the following formula;

Sinθ = opposite / hypotenuse

Sin θ = h / L

L = h / Sin θ

L = 2.8 / Sin 8

L = 2.8 / 0.13917

L = 20.12 m

Therefore, the length of the sloping section of the ramp is 20.12 m

6 0
3 years ago
a line passes through the points (14,5) and (19,15) determine and equation for a perpendicular line that passes through the poin
PSYCHO15rus [73]
The equation of the line thru <span> (14,5) and (19,15)  is found as follows:

                      15-5           5
slope = m = ----------- = ------ = -1
                       19-14         5

Thus, the slope of any line perpendicular to this first line has the slope

m = -1/1 = -1.

Then, using the point-slope form, y-15 = -1(x-19), or y -15 = -x + 19, or
y= -x + 34 (answer)</span>
8 0
4 years ago
An entrepreneur is considering the purchase of a coin-operated laundry. The current owner claims that over the past 5 years, the
Bond [772]

Answer:

a. Z-test of a population mean.

Step-by-step explanation:

The current owner claims that over the past 5 years, the average daily revenue was $675 with a standard deviation of $75.

This means that we have a large sample, which means that we can consider this to be the standard deviation for the population, which eliminates the t-test, leaving options a and c.

Population mean or proportion?

Mean, as a proportion is a value between 0 and 1, while average revenue may have lots of possible values. So the answer is given by option A.

6 0
3 years ago
One non-negative number is the reciprocal of another number. The sum of the two numbers is a minimum. What are the two numbers
Troyanec [42]

The two numbers are 1 and 1.

Let the non-negative number be x and its reciprocal be y = 1/x

The sum of the two numbers is f(x,y) = x + y

= x + 1/x

= f(x)

For f(x) to be minimum, we differentiate it with respect to x and equate it to zero to find the value of x at which irt is minimum.

So, df(x)/dx = d(x + 1/x)/dx

= dx/dx + d(1/x)/dx

= 1 - 1/x²

Equating it to zero, we have

1 - 1/x² = 0

1 = 1/x²

x² = 1

Taking square-root of both sides, we have

x = ±√1

x = ±1

Since x is non-negative x = + 1

We differentiate f(x) again to determine if this value gives a minimum for f(x).

So, d²f(x)/dx² = d(1 - 1/x²)/dx

= d1/dx - d(1/x²)/dx

= 0 - × (-2/x³)

= 2/x³

Substituting x = 1 into the equation,

d²f(x)/dx² = 2/x³

= 2/1³

= 2 > 0.

So x = 1 is a minimum point for f(x)

Since x = 1 and y = 1/x, y = 1/1 = 1

So, the two numbers are 1 and 1.

Learn more about sum of two numbers here:

brainly.com/question/13854139

5 0
3 years ago
According to the Bohr model, the radius of a hydrogen atom is approximately 5.29 × 10/-11 meters. What is this measurement writt
sertanlavr [38]
C. 0.0000000000529 meters
5 0
3 years ago
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