Which measurement statement is correct?

A 99% confidence interval for the mean μ of a population is computed from a random sample and found to be 6 ± 3. We may conclude

valentina_108 [34]

Answer:

A. there is a 99% probability that μ is between 3 and 9.

Step-by-step explanation:

From a random sample, we build a confidence interval, with a confidence level of x%.

The interpretation is that we are x% sure that the interval contains the true mean of the population.

In this problem:

99% confidence interval.

6 ± 3.

So between 6-3 = 3 and 6 + 3 = 9.

So we are 99% sure that the true population mean is between 3 and 9.

So the correct answer is:

A. there is a 99% probability that μ is between 3 and 9.

4 0

3 years ago

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Five times the sum of the digits of a two-digit number is 13 less than the original number. If you reverse the digits in the two

mafiozo [28]

Answer:

The difference of the original two-digit number and the number with reversed digits is 18.

Step-by-step explanation:

Since it's a two digit number, let x represent the tens digit and let y represent the units digit.

Thus, the original two digit number is;

10x + y.

The reverse two digit number is;

10y + x.

We are told that five times the sum of the digits of the two-digit number is 13 less than the original number.

Thus;

5(x + y) = (10x + y) - 13

Multiplying out the bracket gives;

5x + 5y = 10x + y - 13

Rearranging gives;

10x - 5x + y - 5y = 13

5x - 4y = 13 - - - - (3)

Also,we are told that, four times the sum of its two digits is 21 less than the reversed two-digit number. Thus;

4(x + y) = (10y + x) - 21 - - - (4)

Simplifying gives;

4x + 4y = 10y + x - 21

>> 10y - 4y - 4x + x = 21

>> 6y - 3x = 21 - - - (4)

Solving eq(3) and (4) simultaneously gives;

x = 5 and y = 3

Thus,

Original number = 53

Reversed number = 35

Difference between original and reversed number = 53 - 35 = 18

6 0

3 years ago

In a sample of 70 stores of a certain company, 62 violated a scanner accuracy standard. It has been demonstrated that the condi

uysha [10]

Answer:

We need at least 243 stores.

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 of the interval is:

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

For this problem, we have that:

$n = 70, p = \frac{62}{70} = 0.886$

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 $Z = 1.96$ .

Determine the number of stores that must be sampled in order to estimate the true proportion to within 0.04 with 95% confidence using the large-sample method.

We need at least n stores.

n is found when M = 0.04. So

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

$0.04 = 1.96\sqrt{\frac{0.886*0.114}}{n}}$

$0.04\sqrt{n} = 1.96\sqrt{0.886*0.114}$

$\sqrt{n} = \frac{1.96\sqrt{0.886*0.114}}{0.04}$

$(\sqrt{n})^{2} = (\frac{1.96\sqrt{0.886*0.114}}{0.04})^{2}$

$n = 242.5$

Rounding up

We need at least 243 stores.

5 0

3 years ago

-52 times the difference between a number and 14 is equal to the number plus 3

xenn [34]

X=number looked for
we have this equation:
-52(x-14)=x+3
we solve this equation:
-52x+728=x+3
-52x-x=3-728
-53x=-725
x=-725/-53=725/53 ≈13,68

Solution: 725/53

To check:
the difference between 725/53 and 14=725/53 - 14=(725-742)/53=-17/53
-52 times the diference is= -52(-17/53)=884/53
The number plus 3=725/53 + 3=(725+159)/53=884/53

3 0

3 years ago

Given that ∠CEA is a right angle and bisects ∠CEA, which statement must be true?

loris [4]

Given that ∠CEA is a right angle which has been bisected by BE, then:
∠CEB=∠BEA
thus each angle will be complementary to each other, hence the size will be:
90/2=45°
hence the correct statement.
<span>m∠CEB = 45°</span>

8 0

3 years ago

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