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2 years ago

A machine takes 5.4 hours to make 9 parts. At that rate how many parts can the machine make in 25.8 hours

Mathematics

2 answers:

Sveta_85 [38]2 years ago

6 0

9 divided by 5.4 = approx. 1.6
1.6 times 25.8 = 41.28
The machine can make approx. 41.28 parts in 25.8 hours

Sliva [168]2 years ago

4 0

$\frac{5.4}{9} = \frac{25.8}{x}$ Cross multiply.

5.4x=9*25.8

5.4x=232.2 Divide both sides by 5.4

x=43

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It is believed that as many as 23% of adults over 50 never graduated from high school. We wish to see if this percentage is the

JulijaS [17]

Answer:

1) n=48

2) n=298

3) n=426

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$p$ represent the real population proportion of interest

$\hat p$ represent the estimated proportion for the sample

n is the sample size required (variable of interest)

$z$ represent the critical value for the margin of error

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{\hat p(1-\hat p)}{n}})$

Part 1

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 90% of confidence, our significance level would be given by $\alpha=1-0.90=0.10$ and $\alpha/2 =0.05$ . And the critical value would be given by:

$z_{\alpha/2}=-1.64, z_{1-\alpha/2}=1.64$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.1$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

We can assume that the estimated proportion is 0.23 for the 25 to 30 group. And replacing into equation (b) the values from part a we got:

$n=\frac{0.23(1-0.23)}{(\frac{0.1}{1.64})^2}=47.63$

And rounded up we have that n=48

Part 2

The margin of error on this case changes to 0.04 so if we use the same formula but changing the value for ME we got:

$n=\frac{0.23(1-0.23)}{(\frac{0.04}{1.64})^2}=297.7$

And rounded up we have that n=298

Part 3

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 95% of confidence, our significance level would be given by $\alpha=1-0.95=0.05$ and $\alpha/2 =0.025$ . And the critical value would be given by:

$z_{\alpha/2}=-1.96, z_{1-\alpha/2}=1.96$

The margin of error for the proportion interval is given by this formula:

$ME=z_{\alpha/2}\sqrt{\frac{\hat p (1-\hat p)}{n}}$ (a)

And on this case we have that $ME =\pm 0.04$ and we are interested in order to find the value of n, if we solve n from equation (a) we got:

$n=\frac{\hat p (1-\hat p)}{(\frac{ME}{z})^2}$ (b)

We can assume that the estimated proportion is 0.23 for the 25 to 30 group. And replacing into equation (b) the values from part a we got:

$n=\frac{0.23(1-0.23)}{(\frac{0.04}{1.96})^2}=425.22$

And rounded up we have that n=426

3 0

2 years ago

In a certain region, the number of highway accidents increased by 20% over the four years period. How many accidents were there

erma4kov [3.2K]

Equation:

a = 5120

r = 1 + .2 = 1 . 2

f (n ) = 5120 * 1 . 2^n - 1

N = 4 years

f ( 4 ) 5120 * 1 . 2^4 - 1

5120 * 1 . 2^3

We want to know, The number of Highway Accidents in Four Years.

Answer: 8,847 Highway Accidents total:

Hope that helps!!!!!!!!!!! : )

7 0

2 years ago

Is ΔWXZ ≅ ΔYZX? Why or why not? Yes, they are congruent by SAS. Yes, they are both right triangles. No, the triangles share side

gizmo_the_mogwai [7]

I will attached the picture of what you are talking about here. The answer for this problem is: Yes, that they are congruent by SAS. Meaning that the triangles are congruent if their included angles and any pair of corresponding sides are equal in both triangles. In this case, the sides are both 21 cm and this will make the angle equal for both triangles, so that is why they are congruent.