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3 years ago

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A sample of 4 different calculators is randomly selected (without replacement) from a group containing 47 that are defective and

30 that have no defects. What is the probability that all four of the calculators selected are defective?

1 answer:

Anika [276]3 years ago

4 0

Answer:

0.1318 or 13.18%

Step-by-step explanation:

47/77 * 46/76 * 45/75 * 44/74

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What is mean in math

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We considered the differences between the temperature readings in January 1 of 1968 and 2008 at 51 locations in the continental

mr Goodwill [35]

Answer:

$1.1-2.02\frac{4.9}{\sqrt{50}}=-0.30$

$1.1+2.02\frac{4.9}{\sqrt{50}}=2.50$

So on this case the 90% confidence interval would be given by (-0.30;2.50)

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

$\bar X=1.1$ represent the sample mean for the sample

$\mu$ population mean (variable of interest)

s=4.9 represent the sample standard deviation

n=51 represent the sample size

Solution to the problem

The confidence interval for the mean is given by the following formula:

$\bar X \pm t_{\alpha/2}\frac{s}{\sqrt{n}}$ (1)

In order to calculate the critical value $t_{\alpha/2}$ we need to find first the degrees of freedom, given by:

$df=n-1=51-1=50$

Since the Confidence is 0.90 or 90%, the value of $\alpha=0.1$ and $\alpha/2 =0.05$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-T.INV(0.05,50)".And we see that $t_{\alpha/2}=2.02$

Now we have everything in order to replace into formula (1):

$1.1-2.02\frac{4.9}{\sqrt{50}}=-0.30$

$1.1+2.02\frac{4.9}{\sqrt{50}}=2.50$

So on this case the 90% confidence interval would be given by (-0.30;2.50)

8 0

3 years ago

Find the distance between the complex numbers. z1 = 9 - 9i z2 = 10 - 9i

steposvetlana [31]

Answer:

The distance between the two given complex numbers = 9

Step-by-step explanation:

<u><em>Explanation</em></u>:-

<u><em>Step(i):</em></u>-

Given Z₁ = 9 - 9 i and Z₂ = 10 -9 i

Let A and B represent complex numbers Z₁ and Z₂ respectively on the argand plane

⇒ A = Z₁ = x₁ +i y₁ = 9 - 9 i and

B = Z₂ = x₂+ i y₂ = 10 -9 i

Let (x₁ , y₁) = ( 9, -9)

(x₂, y₂) = (10, -9)

<u>Step(ii)</u>:-

<em>The distance between the two points are </em>

A B = $\sqrt{(x_{2} - x_{1})^{2}+(y_{2} - y_{1})^{2} }$

A B = $\sqrt{(10 - 1)^{2}+(-9 - (-9))^{2} }$

AB = $\sqrt{(9)^{2} +(-9+9)^{2} }$

<em> AB = √81 = 9</em>

<u><em>Conclusion:-</em></u>

The distance between the two given complex numbers = 9

<u><em></em></u>

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3 years ago