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VashaNatasha [74]
3 years ago
13

. Suppose that we want to estimate the true proportion of defectives in a very large shipment of adobe bricks, and that we want

to be at least 95% confident that the error is at most 0.04. How large a sample will we need if:
Mathematics
1 answer:
wlad13 [49]3 years ago
8 0

Answer:

A sample of 601 bricks will be needed.

Step-by-step explanation:

In a sample with a number n of people surveyed with a probability of a success of \pi, and a confidence level of 1-\alpha, we have the following confidence interval of proportions.

\pi \pm z\sqrt{\frac{\pi(1-\pi)}{n}}

In which

z is the zscore that has a pvalue of 1 - \frac{\alpha}{2}.

The margin of error is:

M = z\sqrt{\frac{\pi(1-\pi)}{n}}

95% confidence level

So \alpha = 0.05, z is the value of Z that has a pvalue of 1 - \frac{0.05}{2} = 0.975, so Z = 1.96.

How large a sample will we need?

A sample of n bricks will be needed.

n is found when M = 0.04.

We have no estimate for the proportion of defective bricks, so we work with the worst case scenario, which is M = 0.04

M = z\sqrt{\frac{\pi(1-\pi)}{n}}

0.04 = 1.96\sqrt{\frac{0.5*0.5}{n}}

0.04\sqrt{n} = 1.96*0.5

\sqrt{n} = \frac{1.96*0.5}{0.04}

(\sqrt{n})^{2} = (\frac{1.96*0.5}{0.04})^{2}

n = 600.25

Rounding up

A sample of 601 bricks will be needed.

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In an arithmetic series, the sum of the first 12 terms is equal to ten times the sum of the first 3 terms. If the first term is
arlik [135]

Answer:

Step-by-step explanation:

The formula for determining the sum of the first n terms of an arithmetic sequence is expressed as

Sn = n/2[2a + (n - 1)d]

Where

n represents the number of terms in the arithmetic sequence.

d represents the common difference of the terms in the arithmetic sequence.

a represents the first term of the arithmetic sequence.

If a = 5, the expression for the sum of the first 12 terms is

S12 = 12/2[2 × 5 + (12 - 1)d]

S12 = 6[10 + 11d]

S12 = 60 + 66d

Also, the expression for the sum of the first 3 terms is

S3 = 3/2[2 × 5 + (3 - 1)d]

S3 = 1.5[10 + 2d]

S3 = 15 + 3d

The sum of the first 12 terms is equal to ten times the sum of the first 3 terms. Therefore,

60 + 66d = 10(15 + 3d)

60 + 66d = 150 + 30d

66d + 30d = 150 - 60

36d = 90

d = 90/36

d = 2.5

For S20,

S20 = 20/2[2 × 5 + (20 - 1)2.5]

S20 = 10[10 + 47.5)

S20 = 10 × 57.5 = 575

8 0
3 years ago
I the revenue for the week is $2000, and labor cost consists of two workers earning $8 per hour who work 40 hours each, what is
MA_775_DIABLO [31]

Revenue = $2000


Labour cost = 40 x 8 = $320


Percentage = 320/2000 x 100 = 16%


Answer: 16%

4 0
3 years ago
Find the hypotenuse of an isosceles right triangle when the legs each measure 3\sqrt{x} 2inches.
Tresset [83]

The hypotenuse of the right triangle measures 3 units.

<h3>How to find the hypotenuse?</h3>

Here we know that both legs measure:

L  =\frac{3}{\sqrt{2} }

If we use the Pythagorean theorem, we will see that the hypotenuse H can be written as:

H^2 = (\frac{3}{\sqrt{2} } )^2 +  (\frac{3}{\sqrt{2} } )^2 \\\\H^2 = \frac{9}{2} + \frac{9}{2} = \frac{18}{2} = 9\\\\H = \sqrt{9} = 3

Then we conclude that the hypotenuse of the right triangle measures 9 units.

If you want to learn more about right triangles:

brainly.com/question/2217700

#SPJ1

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Answer:

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Step-by-step explanation:

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