Central High School has 5 times as many desktop computers as laptops. The school

Two brands of AAA batteries are tested in order to compare their voltage. The data summary can be found below.

garik1379 [7]

Answer:

The 95% confidence interval would be given by $0.281 \leq \mu_1 -\mu_2 \leq 0.529$

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".

$\bar X_1 =9.2$ represent the sample mean 1

$\bar X_2 =8.8$ represent the sample mean 2

n1=27 represent the sample 1 size

n2=30 represent the sample 2 size

$\sigma_1 =0.3$ population standard deviation for sample 1

$\sigma_2 =0.1$ population standard deviation for sample 2

$\mu_1 -\mu_2$ parameter of interest.

Solution to the problem

The confidence interval for the difference of means is given by the following formula:

$(\bar X_1 -\bar X_2) \pm z_{\alpha/2}\sqrt{\frac{\sigma^2_1}{n_1}+\frac{\sigma^2_2}{n_2}}$ (1)

The point of estimate for $\mu_1 -\mu_2$ is just given by:

$\bar X_1 -\bar X_2 =9.2-8.8=0.4$

Since the Confidence is 0.95 or 95%, the value of $\alpha=0.05$ and $\alpha/2 =0.025$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.025,0,1)".And we see that $t_{\alpha/2}=1.96$

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

$0.4-1.96\sqrt{\frac{0.3^2}{27}+\frac{0.1^2}{30}}=0.281$

$0.4+1.96\sqrt{\frac{6^2}{36}+\frac{7^}{49}}=0.519$

So on this case the 95% confidence interval would be given by $0.281 \leq \mu_1 -\mu_2 \leq 0.529$

6 0

3 years ago

A, B, C and D are four towns.

djverab [1.8K]

Three of the four towns are on the vertices of the triangle ΔCBD, through

which the bearing can calculated.

<h3>Response:</h3>

The bearing of D from B is approximately <u>209.05°</u>

<h3>Method by which the bearing is found;</h3>

From the given information, we have;

AC = AB = 25 km

∠BAC = 90° (definition of angle between north and east)

ΔABC = An isosceles right triangle (definition)

∠ACD = ∠ABC = 45° (base angles of an isosceles right triangle)

$tan(\angle ABD) = \dfrac{45}{25}$

$\angle ABD = arctan \left(\dfrac{45}{25} \right) \approx 60.945^{\circ}$

The bearing of <em>D</em> from <em>B</em> is the angle measured from the north of <em>B</em> to the

direction of <em>D.</em>

<em />

Therefore;

The bearing of D from B ≈ 90° + (180° - 60.945°) = <u>209.05°</u>

Learn more about bearings in mathematics here:

brainly.com/question/10710413

5 0

2 years ago

A bank records deposits as positive numbers and withdrawals as negative numbers. Mike withdrew $60\$60 $60 dollar sign, 60 from

kumpel [21]

Answer:

<ERROR>--------------------------------------------------

Step-by-step explanation:

<ERROR>---------------------

-----------------------

-----

--

------

8 0

2 years ago

Write the equation of the line, in standard form that has an x intercept at (3,0) and y

Nataly [62]

x intercept=a=3
y intercept=b=-2

We need the normal form first

$\\ \rm\bull\rightarrowtail \dfrac{x}{a}+\dfrac{y}{b}=1$

$\\ \rm\bull\rightarrowtail \dfrac{x}{3}-\dfrac{y}{2}=1$

Multiply by 6to bring standard form

$\\ \rm\bull\rightarrowtail 2x-3y=1$

6 0

2 years ago

Solve the following quadratic equation by the square root method. (Y-9)^2=64

enot [183]

Hello!

To solve this, first perform the opposite operation for the last operation (on the left side) on both sides. The last operation of the left side is squaring. Therefore, square root both sides.

$(y - 9)^{2} = 64$

$y - 9 = ±\sqrt{64}$

$y - 9 = ±8$

Please note that you must include ±. This is because the square root of 64 can be either positive or negative, as a square of either a positive or negative number is positive.

Now, add 9 to both sides.

$y = 9±8$

There are 2 solutions from here. One comes from adding 8, and the other subtracting 8. Therefore, the two solutions are:

y = 9 + 8 = 17

y = 9 - 8 = 1

Therefore, your two solutions are 17 and 1.

Hope this helps!

8 0

3 years ago