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2 years ago

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Is rap music more popular among young Indians than among young Asians? A sample survey compared 634 randomly chosen Indians aged

15 to 25 with 567 randomly selected Asians in the same age group. It found that 368 of the Indians and 130 Asians listened to rap music every day. Construct and interpret a 95% confidence interval for the difference between the proportions of black and white young people who listen to rap every day.

1 answer:

BabaBlast [244]2 years ago

8 0

Answer:

Step-by-step explanation:

Confidence interval for the difference in the two proportions is written as

Difference in sample proportions ± margin of error

Sample proportion, p = x/n

Where x = number of successes

n = number of samples

For the indians,

x = 368

n1 = 634

p1 = 368/634 = 0.58

For the asians

x = 130

n2 = 567

p2 = 130/567 = 0.23

Margin of error = z√[p1(1 - p1)/n1 + p2(1 - p2)/n2]

To determine the z score, we subtract the confidence level from 100% to get α

α = 1 - 0.95 = 0.05

α/2 = 0.05/2 = 0.025

This is the area in each tail. Since we want the area in the middle, it becomes

1 - 0.025 = 0.975

The z score corresponding to the area on the z table is 1.96. Thus, confidence level of 95% is 1.96

Margin of error = 1.96 × √[0.58(1 - 0.58)/634 + 0.23(1 - 0.23)/567]

= 1.96 × √0.00038422713 + 0.00031234568)

= 0.052

Confidence interval = 0.58 - 0.23 ± 0.052

Confidence interval = 0.35 ± 0.052

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Which statement follows from the given theorem? Theorem: The diagonal of a parallelogram divides it into two congruent triangles

777dan777 [17]

Answer with explanation:

Theorem : The diagonal of a parallelogram divides it into two congruent triangles.

Properties of parallelogram

1. Opposite sides are equal and parallel.

2. Diagonal bisect each other.

3. Opposite Angles are equal.

If you will look at the first three options

A: Diagonals of a parallelogram bisect opposite angles.→→False(Alternate angles are equal)

B: Consecutive sides of a parallelogram are congruent.→→→False(Opposite sides are congruent)

C: Consecutive angles of a parallelogram are congruent.→→→False(Opposite angles are congruent)

D: Consecutive angles of a parallelogram are supplementary.→→→→True

For,any parallelogram, having vertices , A, B and C and D

Opposite sides are parallel, so

1.∠A + ∠B=180°

2.∠C + ∠B=180°

3.∠C+ ∠D=180°

4. ∠A + ∠D=180°

Option D

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2 years ago

A rectangular area is formed having a perimeter of 40 cm. Determine the length and breadth of the rectangle if it is to enclose

Vilka [71]

Let x and y be the dimensions of the rectangle. If the perimeter is 40, we have

$2(x+y)=40 \iff x+y=20$

We can expression one variable in terms of the others as

$x+y=20 \iff x=20-y$

Since the area is the product of the dimensions, we have

$xy=(20-y)y=-y^2+20y$

This is a parabola facing down, so it's vertex is the maximum:

$f(y)=-y^2+20y \implies f'(y)=-2y+20$

So, the maximum is

$f'(y)=0 \iff -2y+20=0 \iff 2y=20 \iff y=10$

And since we know that $x+y=20$ , we have $x=10$ as well.

This is actually a well known theorem: out of all the rectangles with given perimeter, the one with the greatest area is the square.

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2 years ago

a homeowner wants to carpet two rooms that each measure 12 ft by 15 ft. how many square yards of carpet should be ordered

Lelu [443]

3 feet = 1 yard

12/3 =4

15/3 = 5

4*5 = 20 square yards per room

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2 years ago

A manager at a local manufacturing company has been monitoring the output of one of the machines used to manufacture chromium sh

denpristay [2]

Answer:

0.682 = 68.2% probability that the average length of these 16 shells will be between 116 and 120 centimeters when the machine is operating "properly".

Step-by-step explanation:

To solve this question, we need to understand the normal probability distribution and the central limit theorem.

Normal Probability Distribution:

Problems of normal distributions can be solved using the z-score formula.

In a set with mean $\mu$ and standard deviation $\sigma$ , the z-score of a measure X is given by:

$Z = \frac{X - \mu}{\sigma}$

The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the p-value, we get the probability that the value of the measure is greater than X.

Central Limit Theorem

The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

Normally distributed with a mean of 118 centimeters and a standard deviation of 8 centimeters.

This means that $\mu = 118, \sigma = 8$

Sample of 16 shells

This means that $n = 16, s = \frac{8}{\sqrt{16}} = 2$

What is the probability that the average length of these 16 shells will be between 116 and 120 centimeters when the machine is operating "properly?"

This is the pvalue of Z when X = 120 subtracted by the pvalue of Z when X = 116.

X = 120

$Z = \frac{X - \mu}{\sigma}$

By the Central Limit Theorem

$Z = \frac{X - \mu}{s}$

$Z = \frac{120 - 118}{2}$

$Z = 1$

$Z = 1$ has a pvalue of 0.841

X = 116

$Z = \frac{X - \mu}{s}$

$Z = \frac{116 - 118}{2}$

$Z = -1$

$Z = -1$ has a pvalue of 0.159

0.841 - 0.159 = 0.682

0.682 = 68.2% probability that the average length of these 16 shells will be between 116 and 120 centimeters when the machine is operating "properly".

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2 years ago

Let X represent the amount of time until the next student will arrive in the library parking lot at the university. If we know t

Ber [7]

Answer:

The probability that it will take more than 10 minutes for the next student to arrive at the library parking lot is 0.0821.

Step-by-step explanation:

The random variable <em>X</em> is defined as the amount of time until the next student will arrive in the library parking lot at the university.

The random variable <em>X</em> follows an Exponential distribution with mean, <em>μ</em> = 4 minutes.

The probability density function of <em>X</em> is:

$f_{X}(x)=\lambda e^{\lambda x};\ x\geq 0, \lambda >0$

The parameter of the exponential distribution is:

$\lambda=\frac{1}{\mu}=\frac{1}{4}=0.25$

Compute the value of P (X > 10) as follows:

$P(X>10)=\int\limits^{\infty}_{10}{0.25e^{-0.25x}}\, dx$

$=0.25\times \int\limits^{\infty}_{10}{e^{-0.25x}}\, dx\\=0.25\times |\frac{e^{0.25x}}{-0.25}|^{\infty}_{10}\\=(e^{-0.25\times \infty})-(e^{-0.25\times 10})\\=0.0821$

Thus, the probability that it will take more than 10 minutes for the next student to arrive at the library parking lot is 0.0821.

3 0

2 years ago