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2 years ago

I need help please and thank you

Mathematics

2 answers:

sertanlavr [38]2 years ago

6 0

Corresponding parts of similar triangles are proportional. The area of a triangle is 1/2bh. So DEF’s height is.

6 = 0.5(4h)
12 = 4h
h = 3

We know, therefore, that the ratio of ABC to DEF’s dimensions is 12:4, 3:1. With this, we can deduce that ABC’s height is 9 ( 3 x 3), so ABC’s area is:

0.5(12 x 9) = 54 sq ft

Brums [2.3K]2 years ago

5 0

Well I THINK triangle ABC is just a stretched out version of triangle DEF.

To find the area of a triangle, you multiply base and height, and divide by 2.

Area of DEF is 6, so that means that (4 * x)/2 = 6.

6*2 = 12....

4 * x = 12........

4 * 3 = 12.

x = 3.

Comparing DEF to ABC: ABC's base is 3 times as long as DEF's. So that means the height must be three times as long.

3*3 = 9.

(12 * 9)/2 =54

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3 years ago

When circuit boards used in the manufacture of compact disc players are tested, the long-run percentage of defectives is 5%. Let

vladimir1956 [14]

Answer:

a) P(X ≤ 2) = 0.87

b) P(X ≥ 5) = 0.01

c) P(1 ≤ X ≤ 4) = 0.71

d) P ( X = 0 ) = 0.28

e) σ(X) = 1.09 , E(X) = 1.25

Step-by-step explanation:

Given:

- Let X = the number of defective boards in a random sample of size n = 25, so X ~ Bin(25, 0.05)

Where, n = 25 and p = 0.05

Find:

(a) Determine P(X ≤ 2).(b) Determine P(X ≥ 5).(c) Determine P(1 ≤ X ≤ 4).(d) What is the probability that none of the 25 boards is defective?(e) Calculate the expected value and standard deviation of X.

Solution:

- The probability mass function for a binomial distribution is given by:

P ( X = x ) = nCr * (p)^r * ( 1 - p )^(n-r)

a) P(X ≤ 2):

P(X ≤ 2) = P ( X = 0 ) + P ( X = 1 ) + P ( X = 2 )

= (0.95)^25 + 25*0.05*0.95^24 + 25C2*0.05^2*0.95^23

= 0.87

b) P(X ≥ 5):

P(X ≥ 5) = 1 - [P ( X = 0 ) + P ( X = 1 ) + P ( X = 2 ) + P ( X = 3 ) + P(X=4)

= 1 - [ 0.87 + 25C3*0.05^3*0.95^22 + 25C4*0.05^4*0.95^21]

= 1 - 0.98994

= 0.01

c) P(1 ≤ X ≤ 4):

P(1 ≤ X ≤ 4) = P ( X = 1 ) + P ( X = 2 ) + P ( X = 3 ) + P(X=4)

= ( 0.87 - 0.95^25) + 0.11994

= 0.71

d) P( X = 0 )

P ( X = 0 ) = 0.95^25 = 0.28

e) E(X) & σ(X):

E(X) = n*p

E(X) = 25*0.05 = 1.25

σ(X) = sqrt ( Var (X) )

σ(X) = sqrt ( n*p*(1-p) ) = sqrt ( 25*0.05*0.95 )

σ(X) = 1.09

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2 years ago

Calculate the mean, the variance, and the standard deviation of the following discrete probability distribution. (Negative value

asambeis [7]

<h2>Answer:</h2>

Mean = 24.47

Variance = 108.31

Standard deviation = 10.41

<h2>Step-by-step explanation:</h2>

The probability distribution table has been attached to this response.

<em>(1) To calculate the mean (m)</em>

(a) First multiply each of the values of x by their corresponding probability values.

This is shown in the third column of the table.

(b) The sum of the results in the third column gives the mean of the distribution. i.e

m = ∑xP(x) = 11.52 + 9.36 + 3.15 + 0.44

m = 24.47

<em>(2) To calculate the variance </em> <em>(σ²).</em>

(a) First find the square of the difference between the values of x and the mean (m) calculated in (1b) above. i.e

(x - m)²

The result is shown in the fourth column of the table.

(b) Next, multiply each of the results in the fourth column (x - m)², by their corresponding probability values P(X = x). i.e

(x - m)²(P(X = x))

The result is shown in the fifth column of the table.

σ² = ∑(x - m)²(P(X = x)) = 42.5411 + 0.8427 + 18.8330 + 46.0923

σ² = 108.3091

σ² = 108.31 [to 2 decimal places]

<em>(3) To calculate the standard deviation (σ)</em>

The standard deviation is the square root of the variance of the distribution. Calculate this by finding the square root of the result in (2c) above.

σ = √σ²

σ = $\sqrt{108.31}$

σ = 10.4072

σ = 10.41 [to 2 decimal places]

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2 years ago

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Answer:

x = 67.5°

Step-by-step explanation:

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4x+90 = 360

4x = 360-90

4x = 270

Dividing both sides by 4

x = 67.5°

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3 years ago