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Valentin [98]
2 years ago
10

The Chang's neighbor owns a ready-mix company. The company receives an order for 12.5 cubic yards of concrete. This mixture of c

oncrete contains sand, cement, gravel, and water. For each pound of water, there are 5.5 pounds of sand, 2 pounds of cement, and 7.5 pounds of gravel. Determine how many pounds of cement must be used. Assume a cubic yard of concrete weighs 4,000 pounds.
Mathematics
1 answer:
ella [17]2 years ago
3 0
The quantities in the proportion you give add to 16 pounds, of which 2 pounds are cement. That is, cement constitutes 1/8 of the total weight.

For each yard of concrete, 4000 lb/8 = 500 lb of cement are used.

For 12.5 yards of concrete, 12.5 * 500 = 6,250 pounds of cement will be used.

_____
"yard" in this case is shorthand for "cubic yard".
You might be interested in
For the scotch yoke mechanism shown, the acceleration of point a is defined by the relation a = −1.08sinkt − 1.44coskt, where a
julia-pushkina [17]
<span>Position at t=0.35s is 0.2 m Velocity at t = 0.35s is -0.2 m/s Since this is college level mathematics, the use of the word "acceleration" should indicate to you that you've been given the 2nd derivative of a function specifying the location of point a. And since you've been asked for the velocity, you know that you want the 1st derivative of the function. And since you've also been asked for the position, you also want the function itself. So let's calculate the desired anti-derivatives. f''(t) = -1.08 sin(kt) - 1.44 cos(kt) The integral of f''(t) with respect to t is: f'(t) = (1.08 cos(kt) - 1.44 sin(kt))/k + C In order to find out what C is, we know that at time t=0, v = 0.36 m/s. So let's plug in the values and see what C is: f'(t) = (1.08 cos(kt) - 1.44 sin(kt))/k + C 0.36 = (1.08 cos(3*0) - 1.44 sin(3*0))/3 + C 0.36 = (1.08 cos(0) - 1.44 sin(0))/3 + C 0.36 = (1.08*1 - 1.44*0)/3 + C 0.36 = 0.36 + C 0 = C So the first derivative will be f'(t) = (1.08 cos(kt) - 1.44 sin(kt))/k Now to get the actual function by integrating again. Giving: f(t) = (1.08 sin(kt) + 1.44 cos(kt))/k^2 + C And let's determine what C is: f(t) = (1.08 sin(kt) + 1.44 cos(kt))/k^2 + C 0.16 = (1.08 sin(3*0) + 1.44 cos(3*0))/3^2 + C 0.16 = (1.08 sin(0) + 1.44 cos(0))/9 + C 0.16 = (1.08*0 + 1.44*1)/9 + C 0.16 = 1.44/9 + C 0.16 = 0.16 + C 0 = C So C = 0 and the position function is: f(t) = (1.08 sin(kt) + 1.44 cos(kt))/k^2 So now, we can use out position and velocity functions to get the desired answer: Position: f(t) = (1.08 sin(kt) + 1.44 cos(kt))/k^2 f(t) = (1.08 sin(3*0.35) + 1.44 cos(3*0.35))/3^2 f(t) = (1.08 sin(1.05) + 1.44 cos(1.05))/9 f(t) = (1.08*0.867423226 + 1.44*0.497571048)/9 f(t) = (0.936817084 + 0.716502309)/9 f(t) = 1.653319393/9 f(t) = 0.183702155 So the position of point a at t=0.35s is 0.2 m Now for the velocity: f'(t) = (1.08 cos(kt) - 1.44 sin(kt))/k f'(t) = (1.08 cos(3*0.35) - 1.44 sin(3*0.35))/3 f'(t) = (1.08 cos(1.05) - 1.44 sin(1.05))/3 f'(t) = (1.08*0.497571048 - 1.44*0.867423226)/3 f'(t) = (0.537376732 - 1.249089445)/3 f'(t) = -0.711712713/3 f'(t) = -0.237237571 So the velocity at t = 0.35s is -0.2 m/s</span>
4 0
2 years ago
Two different samples will be taken from the same population of test scores where the population mean and standard deviation are
Alenkinab [10]

Answer:

The sample consisting of 64 data values would give a greater precision.

Step-by-step explanation:

The width of a (1 - <em>α</em>)% confidence interval for population mean μ is:

\text{Width}=2\cdot z_{\alpha/2}\cdot \frac{\sigma}{\sqrt{n}}

So, from the formula of the width of the interval it is clear that the width is inversely proportion to the sample size (<em>n</em>).

That is, as the sample size increases the interval width would decrease and as the sample size decreases the interval width would increase.

Here it is provided that two different samples will be taken from the same population of test scores and a 95% confidence interval will be constructed for each sample to estimate the population mean.

The two sample sizes are:

<em>n</em>₁ = 25

<em>n</em>₂ = 64

The 95% confidence interval constructed using the sample of 64 values will have a smaller width than the the one constructed using the sample of 25 values.

Width for n = 25:

\text{Width}=2\cdot z_{\alpha/2}\cdot \frac{\sigma}{\sqrt{25}}=\frac{1}{5}\cdot [2\cdot z_{\alpha/2}\cdot \sigma]        

Width for n = 64:

\text{Width}=2\cdot z_{\alpha/2}\cdot \frac{\sigma}{\sqrt{64}}=\frac{1}{8}\cdot [2\cdot z_{\alpha/2}\cdot \sigma]

Thus, the sample consisting of 64 data values would give a greater precision

5 0
2 years ago
Read 2 more answers
Write a two step equation involving division and addition that has a solution of x = 25
Tamiku [17]
Start with the solution
x=-25
use the reverse of what they asked
they wanted division and addition
we use multiplication and subtract

ok
x=-25
we can use subtraction and multiplication in any order
minus 10 from both sides
x-10=-35
multiply both sides by 4
4(x-10)=-140
4x-40=-140 is a possible equation
6 0
2 years ago
What is the error due to using linear interpolation to estimate the value of sinxsin⁡x at x = \pi/3? your answer should have at
Serhud [2]
<h3>Answer:</h3>
  • using y = x, the error is about 0.1812
  • using y = (x -π/4 +1)/√2, the error is about 0.02620
<h3>Step-by-step explanation:</h3>

The actual value of sin(π/3) is (√3)/2 ≈ 0.86602540.

If the sine function is approximated by y=x (no error at x = 0), then the error at x=π/3 is ...

... x -sin(x) @ x=π/3

... π/3 -(√3)/2 ≈ 0.18117215 ≈ 0.1812

You know right away this is a bad approximation, because the approximate value is π/3 ≈ 1.04719755, a value greater than 1. The range of the sine function is [-1, 1] so there will be no values greater than 1.

___

If the sine function is approximated by y=(x+1-π/4)/√2 (no error at x=π/4), then the error at x=π/3 is ...

... (x+1-π/4)/√2 -sin(x) @ x=π/3

... (π/12 +1)/√2 -(√3)/2 ≈ 0.026201500 ≈ 0.02620

6 0
2 years ago
Victor baked 30 chocolate chip cookies,18 peanut butter cookies, and 24 sugar cookies. He wants to split them up into equal and
mylen [45]

Answer:

He can make 6 groups

Step-by-step explanation:

To solve this problem first you need to find the GCF or greatest common factor. Now you can put 5 chocolate chip cookies in each group, 3 peanut butter, and 4 sugar cookies. These are all relatively prime so that would be your final answer.

7 0
2 years ago
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