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3 years ago

Find the value of x. A. 65 B. 32.5 C. 118 D. 130

Mathematics

2 answers:

andriy [413]3 years ago

8 0

Answer:

$D.\ \ 130$

Step-by-step explanation:

1. Approach

Refer to the attached diagram of the figure for further explanation. In this problem, one is asked to solve for the degree measure of arc (x). The easiest method to do so is to use the triangle (CAB). One can solve for the measure of angle (<CBA) by using the tangent to radius theorem. Then one can solve for the measure of angle (CAB) by using the base angles theorem. Then one can use the sum of angles in a triangle theorem to solve for angle (<BCA). Finally, one can use the central angles theorem to solve for the arc (x).

2. Find the measure of angles in the triangle

A. Find the measure of angle (<CBE)

As per the given image, lines (BE) and (AE) are tangent. This means that they intersect the circle at exactly one point. A radius is the distance from the center of a circle to the circumference or outer edge of a circle. All radii in a single circle are congruent. The radius of tangent theorem states that, when a tangent intersects a circle at a point of tangency, and a radius also intersects the point of tangency, the angle between the radius and the tangent is a right angle. One can apply this here by stating the following:

$m$

Express angle (<CBE) as the sum of two other angles:

$m$

Substitute with the given and found information:

$m$

$90 = m$

Inverse operations,

$90 = m$

$25= m$

B. FInd the measure of angle (<CAB)

As stated above all radii in a single circle are congruent. This means that lines (CB) and (CA) are equal. Therefore, the triangle (CAB) is an isosceles triangle. One property of an isosceles triangle is the base angles theorem, this theorem states that the angles opposite the congruent sides of an isosceles triangle are congruent. Applying this theorem to the given problem, one can state the following:

$m$

C. Find the measure of angle (<ACB)

The sum of angles in any triangle is (180) degrees. One can apply this theorem here to the given triangle by adding up all of the angles and setting the result equal to (180) degrees. This is shown in the following equation:

$m$

Substitute,

$m$

$25 + 25 + m$

Simplify,

$25 + 25 + m$

$50 + m$

Inverse operations,

$50 + m$

$m$

3. Find the measure of arc (x)

The central angles theorem states that when an angle has its vertex on the center of the circle, its angle measure is equivalent to the measure of the surrounding arc. Thus, one apply this theorem here by stating the following:

$m$

ohaa [14]3 years ago

5 0

Answer:

D. 130

Step-by-step explanation:

The lines are tangent to the circle therefore 90º which makes 65º + 25º. The small triangle with C is iso so the angle of C would be 130 and equivalent to x

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What is 6 divided by 25.2

mr_godi [17]

6/25.2
Multiply both sides by 5 so 25.2 is a whole number:
30/126
and then simplify by dividing by 6:
5/21 which is equal to 0.2381.

Hope this helps :)

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Answer:

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Step-by-step explanation:

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The measure of angle KMJ??

Irina18 [472]

44

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3 years ago

Suppose that a random sample of 10 newborns had an average weight of 7.25 pounds and sample standard deviation of 2 pounds. a. T

frosja888 [35]

Answer:

$z=\frac{7.25-7.5}{\frac{1.4}{\sqrt{10}}}=-0.565$

$p_v =P(Z$

a) If we compare the p value and the significance level given $\alpha=0.05$ we see that $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, so we can conclude that the true average is not significantly less than 7.5.

b) $\chi^2 =\frac{10-1}{1.96} 4 =18.367$

$p_v =P(\chi^2 >18.367)=0.0311$

If we compare the p value and the significance level provided we see that $p_v >\alpha$ so on this case we have enough evidence in order to FAIL reject the null hypothesis at the significance level provided. And that means that the population variance is not significantly higher than 1.96.

Step-by-step explanation:

Assuming this info: "Suppose birth weights follow a normal distribution with mean 7.5 pounds and standard deviation 1.4 pounds"

1) Data given and notation

$\bar X=7.25$ represent the sample mean

$s=1.2$ represent the sample standard deviation

$\sigma=1.4$ represent the population standard deviation

$n=10$ sample size

$\mu_o =7.5$ represent the value that we want to test

$\alpha=0.05,0.01$ represent the significance level for the hypothesis test.

z would represent the statistic (variable of interest)

$p_v$ represent the p value for the test (variable of interest)

2) State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the true mean is less than 7.5, the system of hypothesis would be:

Null hypothesis: $\mu \geq 7.5$

Alternative hypothesis: $\mu < 7.5$

Since we know the population deviation, is better apply a z test to compare the actual mean to the reference value, and the statistic is given by:

$z=\frac{\bar X-\mu_o}{\frac{\sigma}{\sqrt{n}}}$ (1)

z-test: "Is used to compare group means. Is one of the most common tests and is used to determine if the mean is (higher, less or not equal) to an specified value".

3) Calculate the statistic

We can replace in formula (1) the info given like this:

$z=\frac{7.25-7.5}{\frac{1.4}{\sqrt{10}}}=-0.565$

4)P-value

Since is a left tailed test the p value would be:

$p_v =P(Z$

5) Conclusion

Part a

If we compare the p value and the significance level given $\alpha=0.05$ we see that $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, so we can conclude that the true average is not significantly less than 7.5.

Part b

A chi-square test is "used to test if the variance of a population is equal to a specified value. This test can be either a two-sided test or a one-sided test. The two-sided version tests against the alternative that the true variance is either less than or greater than the specified value"

$n=10$ represent the sample size

$\alpha=0.01$ represent the confidence level

$s^2 =4$ represent the sample variance obtained

$\sigma^2_0 =1.96$ represent the value that we want to test

Null and alternative hypothesis

On this case we want to check if the population variance increase, so the system of hypothesis would be:

Null Hypothesis: $\sigma^2 \leq 1.96$

Alternative hypothesis: $\sigma^2 >1.96$

Calculate the statistic

For this test we can use the following statistic:

$\chi^2 =\frac{n-1}{\sigma^2_0} s^2$

And this statistic is distributed chi square with n-1 degrees of freedom. We have eveything to replace.

$\chi^2 =\frac{10-1}{1.96} 4 =18.367$

Calculate the p value

In order to calculate the p value we need to have in count the degrees of freedom , on this case 9. And since is a right tailed test the p value would be given by:

$p_v =P(\chi^2 >18.367)=0.0311$

In order to find the p value we can use the following code in excel:

"=1-CHISQ.DIST(18.367,9,TRUE)"

Conclusion

4 0

3 years ago