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4 years ago

What is the answer

Mathematics

1 answer:

krok68 [10]4 years ago

3 0

Answer:

A circle.

Step-by-step explanation:

Let us say you cut a sphere as shown in the figure, the boundary of the resulting shape you will get will be a circle. Why?

Because a sphere is the same from whichever direction you look at it., and any cross section, you take will be parallel to its diameter ( because the diameter can have any orientation), and since it will be parallel to its diameter, it will also be parallel to the cross section through the diameter. and since the cross section through the diameter is a circle, our cross section will also be a circle .

Imagine orienting the cross section through the diameter, such that it is parallel to the other cross section, and you will see what I mean.

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Answer:

1161

Step-by-step explanation:

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13) The diameter of a plant cell is 1.26 m and the length of a bacterium is 5.1 m. Compare their diameters. (WILL MARK BRANLIEST

kolezko [41]

Answer:

The diameter of the bacterium is 4.05 times the diameter of the plant cell

Step-by-step explanation:

The given parameters both represent diameters

Plant Cell P = 1.26m

Bacterium B = 5.1m

First write out both expressions:

P = 1.26

B = 5.1

Divide B by P

5.1 / 1.26 = 4.04762 Round to 4.05

Multiply both side by P

P * B/P = 4.05 P

B = 4.05 P

This shows that the diameter of the bacterium is 4.048 times the diameter of the plant cell.

8 0

4 years ago

Lisa collects rainwater in a barrel that weighs 25 pounds. When there are 10 gallons of water in the barrel, the total weight of

Zinaida [17]

Answer:

The equation that matches this situation is y = 8.34x + 25 ⇒ B

Step-by-step explanation:

The form of the linear equation is y = m x + b, where

m is the slope (rate of change)

b is the y-intercept (initial value)

The rule of the slope is m = Δy/Δx, where

Δy is the change of y

Δx is the change of x

∵ Lisa collects rainwater in a barrel that weighs 25 pounds

∴ The initial value of the weight is 25 pounds

∴ b = 25

∵ When there are 10 gallons of water in the barrel, the total weight

of the barrel and the water is 108.4 pounds

∴ At x = 10, y = 108.4

∵ When there are 20 gallons of water, the total weight is 191.8 pounds

∴ At x = 20, y = 191.8

→ Find Δx and Δy

∵ Δx = 20 - 10 = 10

∵ Δy = 191.8 - 108.4 = 83.4

→ Substitute them in the rule of the slope above

∴ m = $\frac{83.4}{10}$

∴ m = 8.34

→ Substitute the values of m and b in the form of the equation above

∵ y = 8.34x + 25

∴ The equation that matches this situation is y = 8.34x + 25

6 0

3 years ago

In 2010, the Census Bureau estimated the proportion of all Americans who own their homes to be 0.669. An urban economist wants t

Alexxandr [17]

Answer:

Sample size making use of the Census Bureau: 1,499 American adults.

Sample size without making use of the Census Bureau: 1,692 American adults

ii)

Step-by-step explanation:

The sample size n in Simple Random Sampling is given by

$\bf n=\frac{z^2p(1-p)}{e^2}$

where

z = 1.645 is the critical value for a 90% confidence level (*) 

p= 0.669 is the population proportion given by the Census

e = 0.02 is the margin of error

$\bf n=\frac{(1.645)^2*0.669*0.331}{0.02^2}=1,498.05\approx 1,499$

rounded up to the nearest integer.

(*)This is a point z such that the area under the Normal curve N(0,1) 1nside the interval [-z, z] equals 90% = 0.9

It can be obtained with tables or in Excel or OpenOffice Calc with

NORMSINV(0.95)

If she ignores the Census estimate, the she has to take the largest sample possible that meets the requirements.

Let's show it is obtained when p = 0.5

As we said, the sample size n is

$\bf n=\frac{z^2p(1-p)}{e^2}$

where

e = 0.02 is the error proportion

z = 1.645

hence

$\bf n=\frac{(1.645)^2p(1-p)}{(0.02)^2}=6765.0625p(1-p)=6765.0625p-6765.0625p^2$

taking the derivative with respect to p, we get

n'(p)=6765.0625-2*6765.0625p

and

n'(p) = 0 when p=0.5

By taking the second derivative we see n''(p)<0, so p=0.5 is a maximum of n

This means that if we set p=0.5, we get the maximum sample size for the confidence level required for the proportion error 0.02

Replacing p with 0.5 in the formula for the sample size we get

$\bf n=6765.0625*0.5-6765.0625(0.5)^2=1691.27\approx 1,692$

rounded to the nearest integer.

ii)

When we do not have a proportion but a variable whose approximate standard deviation s is known, then the sample size n in Simple Random Sampling is given by

$\bf n=\frac{z^2s^2}{e^2}$

where

z = 2.241 is the critical value for a 95% confidence level (*) 

s = 7.5 is the estimated population standard deviation

e = 2 hours is the margin of error

$\bf n=\frac{z^2s^2}{e^2}=\frac{(2.241)^2(7.5)^2}{(2)^2}=70.62\approx 71$

(*)This is a point z such that the area under the Normal curve N(0,1) inside the interval [-z, z] equals 95% = 0.95

It can be obtained in Excel or OpenOffice Calc with

NORMSINV(0.9875)

5 0

4 years ago

What is the answer ​

What is the answer