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4 years ago

8

keisha is walking around a track that is 400 yards long. she has walked around the track 5 times so far. how many more yards doe

s she need to walk around to complete 2 miles? PLEASE HELP ME!!

1 answer:

daser333 [38]4 years ago

6 0

3 more times hope I helped

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The ages of a random sample of five university professors are 39, 54, 61, 72, and 59. Using this information, find a 99% confide

blsea [12.9K]

Answer:

$38.898 \leq \sigma^2 \leq 2792.356$

Now we just take square root on both sides of the interval and we got:

$6.237 \leq \sigma \leq 52.843$

Step-by-step explanation:

Data given and notation

34,59,61,71,59

We can calculate the sample standard deviation with the following formula:

$s^2= \frac{\sum_{i=1}^n (X_i -\bar X)^2}{n-1}$

$s= \sqrt{s^2}$

s=12.021 represent the sample standard deviation

$\bar x$ represent the sample mean

n=5 the sample size

Confidence=99% or 0.99

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 mean or variance 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.

The Chi square distribution is the distribution of the sum of squared standard normal deviates .

Calculating the confidence interval

The confidence interval for the population variance is given by the following formula:

$\frac{(n-1)s^2}{\chi^2_{\alpha/2}} \leq \sigma^2 \leq \frac{(n-1)s^2}{\chi^2_{1-\alpha/2}}$

The next step would be calculate the critical values. First we need to calculate the degrees of freedom given by:

$df=n-1=5-1=4$

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical values.

The excel commands would be: "=CHISQ.INV(0.005,4)" "=CHISQ.INV(1-0.005,4)". so for this case the critical values are:

$\chi^2_{\alpha/2}=14.860$

$\chi^2_{1- \alpha/2}=0.207$

And replacing into the formula for the interval we got:

$\frac{(4)(12.021)^2}{14.860} \leq \sigma^2 \leq \frac{(4)(12.021)^2}{0.207}$

$38.898 \leq \sigma^2 \leq 2792.356$

Now we just take square root on both sides of the interval and we got:

$6.237 \leq \sigma \leq 52.843$

3 0

3 years ago

Read 2 more answers

Ann can build a model car in 5 hours, while Sam can build the same model in 15 hours. How many hours would it take for them to b

Yuri [45]

3 hours and 45 minutes

The equation can be solves by adding their two efforts together in a ration equation. See below.

5/x + 15/x = 1

Then give them common denominators and add and solve.

5 0

3 years ago

Meaning of cube root

Nesterboy [21]

Answer:

The cube root of a number is a special value that, when used in a multiplication three times, gives that number. Example: 3 × 3 × 3 = 27, so the cube root of 27 is 3. See: Square Root. Cubes and Cube Roots.

8 0

4 years ago

Where can the prpendicular bisectors of an acute triangle intersect?

ch4aika [34]

<span>The meeting point of the 3 </span>perpendicular bisectors<span> of a triangle's sides is called </span><span>the circumcenter.
</span><span><span>The circumcenter of an </span>acute triangle<span> is always </span>inside<span> the triangle.
so the answer is "a"

Source:
http://www.1728.org/trictr.htm
</span>
</span>

8 0

4 years ago

Please quick responses!!

mamaluj [8]

Answer:

6 7/8 inches

Step-by-step explanation:

The first thing to do is to get the measurements in either inches or feet. You can't have both. Let's go from feet to inches.

3 feet = 36 inches

13.75 feet = 165 inches

Now we can set up a proportion to solve for the number of inches the model is:

$\frac{model}{real}:\frac{1.5}{36} =\frac{x}{165}$

Now we can cross multiply:

36x = 247.5 so

x = 6.875 or 6 7/8 inches

4 0

3 years ago