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2 years ago

True or False? A number is either positive or negative

Mathematics

1 answer:

Dmitry_Shevchenko [17]2 years ago

6 0

True

Positive numbers :- 0 , 1 , 2 , 3 , 4

Negative numbers:- - 1 , - 2 , - 3 , - 4

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A clinical trial tests a method designed to increase the probability of conceiving a girl. In the study 335335 babies were born

strojnjashka [21]

Answer:

The 99% confidence interval estimate of the percentage of girls born is (74.37%, 85.63%).

Usually, 50% of the babies are girls. This confidence interval gives values considerably higher than that, so the method to increase the probability of conceiving a girl appears to be very effective.

Step-by-step explanation:

Confidence Interval for the proportion:

In a sample with a number n of people surveyed with a probability of a success of $\pi$ , and a confidence level of $1-\alpha$ , we have the following confidence interval of proportions.

$\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}$

In which

z is the zscore that has a pvalue of $1 - \frac{\alpha}{2}$ .

For this problem, we have that:

$n = 335, \pi = \frac{268}{335} = 0.8$

99% confidence level

So $\alpha = 0.01$ , z is the value of Z that has a pvalue of $1 - \frac{0.01}{2} = 0.995$ , so $Z = 2.575$ .

The lower limit of this interval is:

$\pi - z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.8 - 2.575\sqrt{\frac{0.8*0.2}{335}} = 0.7437$

The upper limit of this interval is:

$\pi + z\sqrt{\frac{\pi(1-\pi)}{n}} = 0.8 + 2.575\sqrt{\frac{0.8*0.2}{335}} = 0.8563$

For the percentage:

Multiplying the proportions by 100.

The 99% confidence interval estimate of the percentage of girls born is (74.37%, 85.63%).

Usually, 50% of the babies are girls. This confidence interval gives values considerably higher than that, so the method to increase the probability of conceiving a girl appears to be very effective.

7 0

3 years ago

In circle o,find the value of x, rounded to the nearest tenth.

Gemiola [76]

Answer:

$\huge\boxed{x \approx 5.4}$

Step-by-step explanation:

We can break down this problem by first realizing different parts of the circle.

The line which is 8 units long is a chord of the circle.
The line that is 3.6 is almost the radius of the circle
The line that x sits on is the radius.

With this, we can find out if we find the radius of the circle, we have our answer.

We should also note that the angle formed by the 3.6 units long line and the chord is a right angle.

What we need is a way to find the radius of the circle. This will get us x. The radius of a circle will be the length of any line that starts from point O and ends at the circle edge.

If we draw a line connecting the end of the 3.6 line at point O to the end of the 8 unit long chord, we get a triangle! (Image attached for reference).

We can solve for the hypotenuse using the Pythagorean Theorem. This theorem states that:

$\displaystyle a^2 + b^2 = c^2$

Since we know one side is 3.6, we can use that as A. The second side will be 4 since the 3.6 line lies directly in the center of the chord = 8/2 = 4!

$3.6^2 + 4^2 = c^2$
$12.96+16=c^2$
$28.96=c^2$
$\sqrt{28.96} = c$
$5.4 \approx c$

Therefore, since this is the radius of the circle (also the hypotenuse), this can be said for any line that comes from point O onto the edge of the circle.

The line X does just that. Therefore, the value of x is also 5.4.

Hope this helped!