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2 years ago

If D is an n × n diagonal matrix with entries dii, then det D = d11d22 ∙ ∙ ∙ dnn. Verify this theorem for 2 × 2 matrices.

Mathematics

1 answer:

nadya68 [22]2 years ago

8 0

Answer:

Verified

Step-by-step explanation:

Let the diagonal matrix D with size 2x2 be in the form of

$\left[\begin{array}{cc}a&0\\0&d\end{array}\right]$

Then the determinant of matrix D would be

det(D) = a*d - 0*0 = ad

This is the product of the matrix's diagonal numbers

So the theorem is true for 2x2 matrices

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e-lub [12.9K]

The answer would be the last option. :)

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3 years ago

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To save money, a local charity organization wants to target its mailing requests for donations to individuals who are most suppo

mars1129 [50]

Answer:

The 80% confidence interval for difference between two means is (0.85, 1.55).

Step-by-step explanation:

The (1 - α) % confidence interval for difference between two means is:

$CI=(\bar x_{1}-\bar x_{2})\pm t_{\alpha/2,(n_{1}+n_{2}-2)}\times SE_{\bar x_{1}-\bar x_{2}}$

Given:

$\bar x_{1}=M_{1}=6.1\\\bar x_{2}=M_{2}=4.9\\SE_{\bar x_{1}-\bar x_{2}}=0.25$

Confidence level = 80%

$t_{\alpha/2, (n_{1}+n_{2}-2)}=t_{0.20/2, (5+5-2)}=t_{0.10,8}=1.397$

*Use a t-table for the critical value.

Compute the 80% confidence interval for difference between two means as follows:

$CI=(6.1-4.9)\pm 1.397\times 0.25\\=1.2\pm 0.34925\\=(0.85075, 1.54925)\\\approx(0.85, 1.55)$

Thus, the 80% confidence interval for difference between two means is (0.85, 1.55).

3 0

2 years ago

A new car depreciates as soon as you drive it out of the parking lot. A certain car depreciates to half its original value in 4

Alexandra [31]

Answer:

Original price of car = $20,000

Step-by-step explanation:

Let the original price of the car be 'x' dollars.

Given:

Here, the depreciation of the car is occuring exponentially as the value depreciates to half in every four years.

Worth of car after 8 years = $5000

Value after depreciation in 4 years = Half of original value = $\frac{x}{2}$

So, value of car after depreciation in another 4 years = Half of the value after 4 years = $\frac{1}{2}(\frac{x}{2})=\frac{x}{4}$

Therefore, final depreciated value after 8 years is $\frac{x}{4}$ .

But, as per question, final depreciated value is $5000. Thus,

$\frac{x}{4}=5000\\x=5000\times 4\\x=20000$

Therefore, the original price of the car was $20,000.

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2 years ago

A ski lift is designed with a total load limit of 20,000 pounds. It claims a capacity of 100 persons. An expert in ski lifts thi

Yanka [14]

Answer:

0.5 = 50% probability that a random sample of 100 independent persons will cause an overload

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 zscore 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 pvalue, 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.

For the sum of n values of a distribution, the mean is $\mu \times n$ and the standard deviation is $\sigma\sqrt{n}$

An expert in ski lifts thinks that the weights of individuals using the lift have expected weight of 200 pounds and standard deviation of 30 pounds. 100 individuals.

This means that $\mu = 200*100 = 20000, \sigma = 30\sqrt{100} = 300$

If the expert is right, what is the probability that a random sample of 100 independent persons will cause an overload

Total load of more than 20,000 pounds, which is 1 subtracted by the pvalue of Z when X = 20000. So

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

$Z = \frac{20000 - 20000}{300}$

$Z = 0$

$Z = 0$ has a pvalue of 0.5

1 - 0.5 = 0.5

0.5 = 50% probability that a random sample of 100 independent persons will cause an overload

5 0

2 years ago

Domain of the function f(x)=3x/4x^2-4

yaroslaw [1]

Answer:

the complete question in the attached figure

we have that

f(x)=3x/(4x²-4)

we know that

the denominator can not be zero

(4x²-4)=0

4x²=4

x²=1----> x=(+/-)√1

x1=1

x2=-1

the values of x=1 and x= -1 make the denominator zero, therefore they do not belong to the domain of the function

the answer is

the domain of the function is all real numbers except 1 and -1

8 0

3 years ago