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Vilka [71]
2 years ago
14

A construction company needs to remove 10 tons of dirt from a construction site. They can remove 2/5 tons of dirt each hour. How

long will take to remove the dirt?
Mathematics
1 answer:
vfiekz [6]2 years ago
5 0

Step-by-step explanation:

You can just divide 10 by 2/5 and you get 25 or try this

Set up proportions and cross multiply 2/5 / 1  =  10/x which you can read as : if 2/5 can be done in 1 hour then 10 tons can be done in x hours cross multiplying, you get 2x/5 = 10  and x = 25

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KonstantinChe [14]
Berro can get 3 gallons of gas
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3 years ago
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Is the equation 4y+6=5y-8 true,false,or open
svlad2 [7]

True.

Work is in attached sheet! <3

5 0
3 years ago
In a study of 420,095 Danish cell phone users, 135 subjects developed cancer of the brain or nervous system (based on data from
Maksim231197 [3]

Answer:

z=\frac{0.0003214 -0.00034}{\sqrt{\frac{0.00034(1-0.00034)}{420095}}}=-0.654  

p_v =2*P(Z  

So the p value obtained was a very high value and using the significance level given \alpha=0.005 we have p_v>\alpha so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can say that the true proportion not differs significantly from the specified value of 0.00034 or 0.034%.

Step-by-step explanation:

1) Data given and notation  

n=420095 represent the random sample taken

X=135 represent the subjects developed cancer of the brain or nervous system (based on data from the Journal of the National Cancer Institute as reported in USA Today)

\hat p=\frac{135}{420095}=0.0003214 estimated proportion of subjects developed cancer of the brain or nervous system (based on data from the Journal of the National Cancer Institute as reported in USA Today)

p_o=0.00034 is the value that we want to test

\alpha=0.005 represent the significance level

Confidence=99.5% or 0.995

z would represent the statistic (variable of interest)

p_v represent the p value (variable of interest)  

2) Concepts and formulas to use  

We need to conduct a hypothesis in order to test the claim that the brain or nervous system at a rate that is different from the rate of 0.0340% :  

Null hypothesis:p=0.00034  

Alternative hypothesis:p \neq 0.00034  

When we conduct a proportion test we need to use the z statistic, and the is given by:  

z=\frac{\hat p -p_o}{\sqrt{\frac{p_o (1-p_o)}{n}}} (1)  

The One-Sample Proportion Test is used to assess whether a population proportion \hat p is significantly different from a hypothesized value p_o.

3) Calculate the statistic  

Since we have all the info requires we can replace in formula (1) like this:  

z=\frac{0.0003214 -0.00034}{\sqrt{\frac{0.00034(1-0.00034)}{420095}}}=-0.654  

4) Statistical decision  

It's important to refresh the p value method or p value approach . "This method is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.  

The significance level provided \alpha=0.005. The next step would be calculate the p value for this test.  

Since is a bilateral test the p value would be:  

p_v =2*P(Z  

So the p value obtained was a very high value and using the significance level given \alpha=0.005 we have p_v>\alpha so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can say that the true proportion not differs significantly from the specified value of 0.00034 or 0.034%.  

4 0
3 years ago
A parking lot has 916 parking spaces that are shaped like parallelograms. The base of each space is 10 feet, and the height of e
dmitriy555 [2]
The area of a parallelogram is A=bh

A=10(18.5) \\ A=185

I am assuming you're asking for the entire parking lot, so you would have to multiply the above area by 916

185(916) = 169,460  ft^{2}

So the answer is (D)

7 0
3 years ago
Help me out here please. find the area
Vinvika [58]

Answer: 56

Step-by-step explanation: first, you have to find the area of one triangle. The formula is A=bh1/2 . When you do that, you get 14. 14 is only one triangle, so multiply it by 4 and you get your answer, 56.

6 0
3 years ago
Read 2 more answers
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