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2 years ago

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A supervisor records the repair cost for 22 randomly selected VCRs. A sample mean of $75.50 and standard deviation of $18.07 are

subsequently computed. Determine the 99% confidence interval for the mean repair cost for the VCRs. Assume the population is approximately normal. Step 1 of 2 : Find the critical value that should be used in constructing the confidence interval. Round your answer to three decimal places.

1 answer:

VashaNatasha [74]2 years ago

8 0

Answer:

The t value for 99% CI for 21 df is 2.831.

The critical value that should be used in constructing the confidence interval is (64.593, 86.407).

Step-by-step explanation:

Now the sample size is less than 30 and also population standard deviation is not known.

Then we will use t distribution to find CI

t value for 99% CI for 21 df is TINV(0.01,21)=2.831

The margin of error is $E=t\times\frac{s}{\sqrt{n}}\\\\=2.831\times\frac{18.07}{\sqrt{22}}\\\\=10.907$

Hence CI is $CI=\overline{x} \pm E\\\\ =75.50 \pm 10.907\\\\=(64.593,86.407 )$

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Find the perimeter of a square with side a. Are the perimeter of the square and the length of its side directly proportional qua

inna [77]

The perimeter of a square with side a = 7.2 cm is 28.8 cm. Yes there exists a direct proportional relationship between Side length and Perimeter of square

<h3><u>Solution:</u></h3>

Given that side of square "a" = 7.2 cm

We have to find the perimeter of square

<em><u>The perimeter of square is given as:</u></em>

Perimeter of square = 4a

Where "a" represents the length of side of square

Substituting the given value a = 7.2 cm in above formula, we get perimeter of square

Perimeter of square = 4(7.2) = 28.8 cm

<em><u>Are the perimeter of the square and the length of its side directly proportional quantities?</u></em>

$\begin{array}{l}{\text { perimeter of square }=4 a=4 \times \text { length of side }} \\\\ {\frac{\text { perimeter of square }}{\text { length of side }}=4}\end{array}$

The Perimeter is equal to a constant times the Side length, or the Perimeter divided by the Side length is equal to four. So this is definitely a proportional relationship between Side length and Perimeter.

Two values are said to be in direct proportion when an increase in one results in an increase in the other.

So when length of sides increases, perimeter also increases

Hence perimeter and length of side of square are directly propotional quantities

4 0

3 years ago

The length of a rectangle is four times its width. If the area of the rectangle is 324m^2, find its perimeter.

Anuta_ua [19.1K]

Answer:

$perimeter=90$

Step-by-step explanation:

We know that the length is four times the width, so:

$l=4w$

We also know the area, which is 324 m². The formula for area:

$A=l*w$

Insert the known values:

$324=(4w)*w$

Solve for w. Simplify by removing parentheses:

$324=4w*w\\324=4w^2$

Divide 4 from both sides to isolate the variable:

$\frac{324}{4}=\frac{4w^2}{4} \\\\81=w^2$

Find the square root of both sides:

$\sqrt{81} =\sqrt{w^2} \\\\w=9$

The width is 9 m.

We know the width. Now find the length by using the area formula and inserting known values:

$324=l*9$

Solve for l. Divide both sides by 9:

$\frac{324}{9}=\frac{l*9}{9}\\\\ l=36$

The length of the rectangle is 36. (You can check: 4 times 9 is 36)

Now find the perimeter:

$P=2l+2w$

Insert values:

$P=2(36)+2(9)\\\\P=72+18\\\\P=90$

The perimeter is 90 m.

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3 years ago

Which expression is equivalent to the given expression?

Tatiana [17]

Answer:

The answer is 4a-12

Step-by-step explanation:

Hope this helped :>

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3 years ago

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Define a function f on a set of real numbers as follows: f(x) = 3x − 1 x , for each real number x ≠ 0 Prove that f is one-to-one

dalvyx [7]

Answer with Step-by-step explanation:

We are given that

$f(x)=\frac{3x-1}{x}$

For each real number $x\neq 0$

To prove that f is one -to-one.

Proof:Let $x_1$ and $x_2$ be any nonzero real numbers such that

$f(x_1)=f(x_2)$

By using the definition of f to rewrite the left hand side of this equation

$f(x_1)=\frac{3x_1-1}{x_1}$

Then, by using the definition of f to rewrite the right hand side of this equation of $f(x_1)=f(x_2)$

$f(x_2)=\frac{3x_2-1}{x_2}$

Equating the expression then we get

$\frac{3x_1-1}{x_1}=\frac{3x_2-1}{x_2}$

$3x_1x_2-x_2=3x_2x_1-x_1$

$3x_1x_2-3x_1x_2+x_1=x_2$

$x_1=x_2$

Therefore, f is one-to-one.

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3 years ago

zhannawk [14.2K]

Answer:

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Step-by-step explanation:

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3 years ago