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3 years ago

3 points

Mathematics

1 answer:

ElenaW [278]3 years ago

6 0

Answer:

The density of the metal C is 2 g/cm³

Step-by-step explanation:

The parameters of the two metals are;

The density of the Metal A = 2.4 g/cm³

The density of the Metal B = 1.8 g/cm³

The ratio in which their masses are combined to make the metal C= 2:3

The mass of the metal C, m = 60 grams

Let, 'x', represent the mass of the metal A in the 60 grams of the metal C and let 'y' represent the mass of the metal B in the 60 grams of the metal C

Let the ratio of the metals A and B in the metal C = x:y = 2:3

Therefore;

The mass of the metal A in the metal C, x = (2/(3 + 2)) × 60 g = 24 g

The volume of the metal A in the metal C, V₁ = (24 g)/(2.4 g/cm³) = 10 cm³

The mass of the metal B in the metal C, y = (3/(3 + 2)) × 60 g = 36 g

The volume of the metal B in the metal C, V₂ = (36 g)/(1.8 g/cm³) = 20 cm³

The volume of the metal C, V = V₁ + V₂ = 10 cm³ + 20 cm³ = 30 cm³

The density of the metal C = ρ = m/V

ρ = (60 g)/(30 cm³) = 2 g/cm³

The density of the metal C, ρ = 2 g/cm³

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The new ointment was applied to four locations, and a control was applied to the other four. How many different choices were the

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Answer:

there are 70 possible choices for the four locations to apply the new ointment

Step-by-step explanation:

Since we have a total of 8 locations ( 4 to the new ointment and 4 to the control) , each one can be chosen and since the order of the locations that are chosen for the new ointment is not relevant , then we know that the number of choices is given by the number of combinations of 4 elements in 8

number of combinations = 8 possible locations to the first ointment * 7 possible locations to the second ( since the first one was already located) * 6 to the third * 5 locations for the fourth / number of times the same combination is repeated ( the same locations but in different positions) = 8*7*6*5 / (4 possible positions for the first ointment* 3 possible positions to the second ointment (since the first one was already located * 2 possible positions of the third * 1 possible position of the fourth)

therefore

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3 years ago

Eric kept track of his days is a journal:

Leya [2.2K]

Answer:

Step-by-step explanation:

5 percent * 60 =

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2 years ago

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Suppose that y varies directly with x and y=5 when x=6. What is y when x=5? Be sure to simplify your answer.

Charra [1.4K]

Answer:

y = $\frac{25}{6}$

Step-by-step explanation:

Given y varies directly with x then the equation relating them is

y = kx ← k is the constant of variation

To find k use the condition y = 5 when x = 6

k = $\frac{y}{x}$ = $\frac{5}{6}$

y = $\frac{5}{6}$ x ← equation of variation

When x = 5, then

y = $\frac{5}{6}$ × 5 = $\frac{25}{6}$

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3 years ago

Use the given information to find the p-value. Also, use a 0.05 significance level and state the conclusion about the null hyp

Hatshy [7]

Answer:

We can assume that the statistic is $z_{calc}=0.78$

$p_v = 2* P(z>0.78) = 0.435$

So the p value obtained was a very high value and using the significance level given $\alpha=0.05$ we have $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can said that at 5% of significance the true proportion of interest is not different from 3/5

Step-by-step explanation:

Concepts and formulas to use

We need to conduct a hypothesis in order to test the claim that the true proportion is equal to 3/5 or not.:

Null hypothesis: $p=3/5$

Alternative hypothesis: $p \neq 3/5$

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 $p_o$ .

Calculate the statistic

We can assume that the statistic is $z_{calc}=0.78$

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 $\alpha=0.05$ . The next step would be calculate the p value for this test.

Since is a bilateral test the p value would be:

$p_v = 2* P(z>0.78) = 0.435$

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3 years ago

Which one is correct for this question need help please

emmainna [20.7K]

Answer:

A is correct, 7 units. Hope this helps! :)

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2 years ago