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2 years ago

♦♦Will mark brainliest♦♦

Mathematics

2 answers:

Blababa [14]2 years ago

8 0

I think the answer is 8.5 h

Grace [21]2 years ago

4 0

Answer:

8.5 h

Step-by-step explanation:

55.75

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A simple random sample of items resulted in a sample mean of . The population standard deviation is . a. Compute the confidence

Varvara68 [4.7K]

Answer:

(a): The 95% confidence interval is (46.4, 53.6)

(b): The 95% confidence interval is (47.9, 52.1)

(c): Larger sample gives a smaller margin of error.

Step-by-step explanation:

Given

$n = 30$ -- sample size

$\bar x = 50$ -- sample mean

$\sigma = 10$ --- sample standard deviation

Solving (a): The confidence interval of the population mean

Calculate the standard error

$\sigma_x = \frac{\sigma}{\sqrt n}$

$\sigma_x = \frac{10}{\sqrt {30}}$

$\sigma_x = \frac{10}{5.478}$

$\sigma_x = 1.825$

The 95% confidence interval for the z value is:

$z = 1.960$

Calculate margin of error (E)

$E = z * \sigma_x$

$E = 1.960 * 1.825$

$E = 3.577$

The confidence bound is:

$Lower = \bar x - E$

$Lower = 50 - 3.577$

$Lower = 46.423$

$Lower = 46.4$ --- approximated

$Upper = \bar x + E$

$Upper = 50 + 3.577$

$Upper = 53.577$

$Upper = 53.6$ --- approximated

So, the 95% confidence interval is (46.4, 53.6)

Solving (b): The confidence interval of the population mean if mean = 90

First, calculate the standard error of the mean

$\sigma_x = \frac{\sigma}{\sqrt n}$

$\sigma_x = \frac{10}{\sqrt {90}}$

$\sigma_x = \frac{10}{9.49}$

$\sigma_x = 1.054$

The 95% confidence interval for the z value is:

$z = 1.960$

Calculate margin of error (E)

$E = z * \sigma_x$

$E = 1.960 * 1.054$

$E = 2.06584$

The confidence bound is:

$Lower = \bar x - E$

$Lower = 50 - 2.06584$

$Lower = 47.93416$

$Lower = 47.9$ --- approximated

$Upper = \bar x + E$

$Upper = 50 + 2.06584$

$Upper = 52.06584$

$Upper = 52.1$ --- approximated

So, the 95% confidence interval is (47.9, 52.1)

Solving (c): Effect of larger sample size on margin of error

In (a), we have:

$n = 30$ $E = 3.577$

In (b), we have:

$n = 90$ $E = 2.06584$

Notice that the margin of error decreases when the sample size increases.

4 0

2 years ago

What is the sum of the interior angles of the polygon pictured below?

Lostsunrise [7]

Answer:

Step-by-step explanation: IM MAKING A GUESS IF ITS WRONG IM SORRY I TIRED

5 0

2 years ago

Use the parabola tool to graph the quadratic function y=-1? - 2.0 +8

Andreas93 [3]

Answer:

see explanation

Step-by-step explanation:

I don't have graphing facilities but can give you the vertex and 1 other point.

Given a parabola in standard form

y = ax² + bx + c ( a ≠ 0 )

Then the x- coordinate of the vertex is

x = - $\frac{b}{2a}$

y = - x² - 2x + 8 ← is in standard form

with a = - 1 and b = - 2 , then

x = - $\frac{-2}{-2}$ = - 1

Substitute x = - 1 into the equation for corresponding value of y

y = - (- 1)² - 2(- 1) + 8 = - 1 + 2 + 8 = 9

vertex = (- 1, 9 )

To obtain another point substitute any value for x into the equation

x = 0 : y = 0 - 0 + 8 , then (0, 8 ) is a point on the graph

x = 2 : y = - (2)² - 2(2) + 8 = - 4 - 4 + 8 = 0 then (2, 0 ) is a point on the graph

3 0

2 years ago

What’s the correct answer

matrenka [14]

Show a picture of it I can’t see one

5 0

2 years ago

Find the average rate of change of the function over the given interval.

Minchanka [31]

Answer:

Average rate of change = 20.2

Rate of change at the left endpoint : f' (5) = 4t = 20

Rate of change at the right endpoint : f' (5.1) = 4*5.1 = 20.4

Step-by-step explanation:

The average rate of change of the function

F(t) = 2t^2 - 1 , [ 5,5.1 ]

solution

$\frac{f(5.1)-f(5)}{5.1 - 5}$ = $\frac{2*(5.1)^2-1-(2*5^2-1)}{0.1}$ = [ 2 ( 26.01 - 25 ) / 0.1 ]

= 2.02 / 0.1 = 20.2

Rate of change at the left endpoint : f' (5) = 4t = 20

Rate of change at the right endpoint : f' (5.1) = 4*5.1 = 20.4

6 0

3 years ago