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3 years ago

The mean of a normally distributed dataset is 12, and the standard deviation is 2.

1 answer:

5 0

So lets do it like this:
z = (X-Mean)/SD
z1 = (8-12)/2 = - 2 
z2 = (16-12)/2 = + 2 
According to the Empirical Rule 68-95-99.7 
Mean more or less 2SD covers 95% of the values 
So the percentage of data points falling between 8 and 16 = 95%
I hope this can help

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Musya8 [376]

Answer:

Step-by-step explanation:

A straight line adds up to 180 degrees, therefore 3x+6x = 180

9x = 180

x = 20

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3 years ago

The radius of a sphere is 1/3 ft what is the approximate volume of the sphere

Katen [24]

Answer:

0.16 ft

Step-by-step explanation:

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2 years ago

Joe is building a post for his mailbox. To find the correct dimensions, he needs to expand this expression: (x-3) (x-9) (x-4) Se

kolbaska11 [484]

Answer:

$(x-3)(x-9)(x-4)=x^3-16x^2+75x-108$

Step-by-step explanation:

Given:

The expression to expand is given as:

$(x-3)(x-9)(x-4)$

Let us expand the first two binomials of the given expression using FOIL method.

The FOIL method states that:

$(a + b)(c + d) = ac + ad + bc + bd$

$(x-3)(x-9)=(x\times x)+(x\times -9)+(-3\times x)+(-3\times -9)\\\\(x-3)(x-9)=x^2-9x-3x+27=x^2-12x+27$

Now, let us multiply the result with the remaining binomial. Multiplying each term of the trinomial with each term of the binomial, we get:

$(x^2-12x+27)(x-4)\\\\= (x^2\times x)+ (x^2\times -4)+(-12x\times x)+(-12x\times -4)+(27\times x)+(27\times -4)\\\\=x^3-4x^2-12x^2+48x+27x-108\\\\=x^3-16x^2+75x-108...........(\because-12x^2-4x^2=-16x^2,48x+27x=75x)$

Therefore, the equivalent expression after expanding is given as:

$(x-3)(x-9)(x-4)=x^3-16x^2+75x-108$

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3 years ago

To fit between two windows, the width of a bookshelf must be no greater than feet. Mrs. Aguilar purchases a bookshelf that is 77

kozerog [31]

Given:
width of bookshelf no greater than 6 1/2 feet
purchased bookshelf that is 77 inches wide

We need to find the equivalent value in feet of the purchased bookshelf.

1 foot is equal to 12 inches

77 inches * 1 foot/12 inches = 77 ft/12 = 6 5/6 ft

Or we can convert the feet into inches:

6 1/2 feet convert to improper fraction.

((6*2)+1)/2 = 13/2 feet

13/2 ft * 12 inches/1ft = (13 * 12)/2 = 156/2 = 78 inches

Compare the maximum width of 78 inches to the actual width of 77 inches.

The purchased bookshelf can fit between two windows.

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3 years ago

Community college students conduct a survey at their college. They ask "Do you plan to transfer to a university to pursue a bacc

Tamiku [17]

Answer:

$0.8 - 2.58\sqrt{\frac{0.8(1-0.8)}{100}}=0.697$

$0.8 + 2.58\sqrt{\frac{0.8(1-0.8)}{100}}=0.903$

The 99% confidence interval would be given by (0.697;0.903)

And the best option is : 0.697 to 0.903

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

Solution to the problem

For this case the conditions we have the conditions to assume a normal distribution for the population proportion since:

np=100*0.8=80 >10 , n(1-p) = 10*(1-0.8) =20 >10

In order to find the critical value we need to take in count that we are finding the interval for a proportion, so on this case we need to use the z distribution. Since our interval is at 99% of confidence, our significance level would be given by $\alpha=1-0.99=0.01$ and $\alpha/2 =0.005$ . And the critical value would be given by: