A doctor at a local hospital is interested in estimating the birth weight of infants. How large a sample must she select if she desires to be 90% confident that her estimate is within 4 ounces of the true mean

Answers

Answer 1

Answer:

Answer:

The minimum sample size needed is $n = ((1.96√(\sigma))/(4))^2$ . If n is a decimal number, it is rounded up to the next integer. $\sigma$ is the standard deviation of the population.

Step-by-step explanation:

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = (1 - 0.9)/(2) = 0.05$

Now, we have to find z in the Z-table as such z has a p-value of $1 - \alpha$ .

That is z with a pvalue of $1 - 0.05 = 0.95$ , so Z = 1.645.

Now, find the margin of error M as such

$M = z(\sigma)/(√(n))$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

How large a sample must she select if she desires to be 90% confident that her estimate is within 4 ounces of the true mean?

A sample of n is needed, and n is found when M = 4. So

$M = z(\sigma)/(√(n))$

$4 = 1.96(\sigma)/(√(n))$

$4√(n) = 1.96√(\sigma)$

$√(n) = (1.96√(\sigma))/(4)$

$(√(n))^2 = ((1.96√(\sigma))/(4))^2$

$n = ((1.96√(\sigma))/(4))^2$

The minimum sample size needed is $n = ((1.96√(\sigma))/(4))^2$ . If n is a decimal number, it is rounded up to the next integer. $\sigma$ is the standard deviation of the population.

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Answers

Answer: 16^2 + 12^2

Step-by-step explanation:

20^2 = 400

16 x 16 = 256

12 x 12 = 144

256 + 144 = 400

A rectangle is inscribed in a circle.Calculate the area of the circle. Use 3.14 for π. Round to the nearest hundredth.

1___ Square centimeters

2 Calculate the area of the rectangle.

3. Calculate the area of the shaded region. Use 3.14 for π. Round to the nearest hundredth.

Answers

Answer:

1. The area of the circle is 132.67 square centimeters

2. The area of the rectangle is 60 square centimeters

3. The area of the shaded region is 72.67 square centimeters

Step-by-step explanation:

* Lets explain how to solve the problem

- A rectangle is inscribed in a circle, that means the vertices of the

rectangle lie on the circumference of the circle

∴ The diagonal of the rectangle = the diameter of the circle

- From the attached figure

∵ The diameter of the circle = 13 cm

∵ The radius of the circle is half the diameter

∴ The radius of the circle = 1/2 (13) = 6.5 cm

- The area of the circle = πr²

∵ π = 3.14

∴ The area of the circle = 3.14 × (6.5)² = 132.67 cm²

1. The area of the circle is 132.67 square centimeters

- The area of any rectangle = length × width

∵ The length of the rectangle is 12 cm

∵ The width of the rectangle is 5 cm

∴ The area of the rectangle = 12 × 5 = 60 cm²

2. The area of the rectangle is 60 square centimeters

- The area of the shaded region is the difference between the

area of the circle and the area of the rectangle

∵ The area of the circle = 132.67 cm²

∵ The area of the rectangle = 60 cm²

∵ The area of the shaded region = area of circle - area of rectangle

∴ The area of the shaded region = 132.67 - 60 = 72.67 cm²

3. The area of the shaded region is 72.67 square centimeters

What is nearest tenth of 0.273

Answers

Answer:

0.3

To round 0.273 to the nearest tenth consider the hundredths’ value of 0.273, which is 7 and equal or more than 5. Therefore, the tenths value of 0.273 increases by 1 to 3.

0.273 rounded to the nearest tenth = 0.3

I would like to create a rectangular vegetable patch. The fencing for the east and west sides costs $4 per foot, and the fencing for the north and south sides costs only $2 per foot. I have a budget of $176 for the project. What are the dimensions of the vegetable patch with the largest area I can enclose?

Answers

x = E/W dimension
y = N/S dimension

4x + 4x + 2y + 2y = 64
8x + 4y = 64
4y = 64 - 8x
y = 16 - 2x

Area = xy = x(16 - 2x) = 16x - 2x^2

Maximum of y = ax^2 + bx + c is when x = -b / 2a

so x = -16 / -4 = 4

A garden is in the shape of a circle with a radius of 10 feet. Edging is place around the garden. How much edging, in feet, is needed togo around the garden? Round your answer to the nearest whole number. Use 3. 14 for TT.
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