I need help with 3-14

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

When a sprinkler is installed in the ground, the spray of water goes up and falls in the pattern of a parabola. The height, in i

poizon [28]

Answer:

96feet

Step-by-step explanation:

Given the height, in inches, of a spray of water is given by the equation ℎ(x)=160−16x^2

x is the number of feet away from the sprinkler head the spray

To get the height of the spray 2 feet away from the sprinkler head, we will simply substitute x =2 into the function and et the height h as shown;

From the equation

ℎ(x)=160−16x^2

h(2) = 160-16(2)²

h(2) = 160-16(4)

h(2) = 160-64

h(2) = 96feet

Hence the height will be 96feet if the spray is 2feet away from the sprinklers head

8 0

3 years ago

Jasper has an annual salary of $71,000, and his company pays him twice a month. What is the gross income per paycheck that Jaspe

Elan Coil [88]

Divide $71,000 by 24 because there are 12 months in a year and he gets paid 2 times a month. I got $2,958.33

5 0

3 years ago

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What is 10th term in 3,8,13,18?

skad [1K]

3+5=8+5=13 so if you keep doing this you will get 48 which is the answer

5 0

3 years ago

4r+8+5=-15-3r ANSWER NUMBER FORM NO WORDS AT ALL

wolverine [178]

Answer:

r = -4

Step-by-step explanation:

Step 1: Write out equation

4r + 8 + 5 = -15 - 3r

Step 2: Combine like terms

4r + 13 = -15 - 3r

Step 3: Add 3r to both sides

7r + 13 = -15

Step 4: Subtract 13 on both sides

7r = -28

Step 5: Divide both sides by 7

r = -4

7 0

3 years ago

Read 2 more answers