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2 years ago

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A scuba diver used the expression below to describe his position in relation to sea level.2 + (negative 20) + 8Which statement c

ould describe the diver's movements?

1 answer:

Sloan [31]2 years ago

7 0

Answer:

Starting on a platform 2 feet above sea level, dive down to a location that is 18 feet below sea level, and then rise 8 feet.

Step-by-step explanation:

Using the 2 + (-20) + 8 to describe movement relative to sea level ;

2 can be taken as the starting point, positive values represents elevation above sea level ;

2 can be taken as 2 feet platform above sea level ;

- 20 represents distance dived from platform, negative signifies elevation below sea level ; the distance dived relative to sea level is (-20 + platform height)

(-20 + 2) = - 18

8 feets means a final elevation of 8 above sea level (positive value).

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Therefore 4225=s^2

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A random sample from a normal population is obtained, and the data are given below. Find a 90% confidence interval for . 114 157

melamori03 [73]

Answer:

$103.160 \leq \sigma \leq 187.476$

And the upper bound rounded to the nearest integer would be 187.

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 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 .

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

$\mu$ population mean (variable of interest)

s represent the sample standard deviation

n represent the sample size

Solution to the problem

Data given: 114 157 203 257 284 299 305 344 378 410 421 450 478 480 512 533 545

The confidence interval for the population variance $\sigma^2$ is given by the following formula:

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

On this case we need to find the sample standard deviation with the following formula:

$s=sqrt{\frac{\sum_{i=1}^{17} (x_i -\bar x)^2}{n-1}}$

And in order to find the sample mean we just need to use this formula:

$\bar x =\frac{\sum_{i=1}^n x_i}{n}$

The sample mean obtained on this case is $\bar x= 362.941$ and the deviation s=132.250

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

$df=n-1=17-1=16$

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 tabel to find the critical values.

The excel commands would be: "=CHISQ.INV(0.05,16)" "=CHISQ.INV(0.95,16)". so for this case the critical values are:

$\chi^2_{\alpha/2}=26.296$

$\chi^2_{1- \alpha/2}=7.962$

And replacing into the formula for the interval we got:

$\frac{(16)(132.250)^2}{26.296} \leq \sigma \leq \frac{(16)(132.250)^2}{7.962}$

$10641.959 \leq \sigma^2 \leq 35147.074$

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

$103.160 \leq \sigma \leq 187.476$

And the upper bound rounded to the nearest integer would be 187.

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2 years ago

A quality control engineer at a potato chip company tests the bag filling machine by weighing bags of potato chips. Not every ba

Ahat [919]

Answer:

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Step-by-step explanation:

Information provided

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$\hat p=\frac{21}{100}=0.21$ estimated proportion of overfilled bags

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z would represent the statistic

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We need to conduct a hypothesis in order to test if the true proportion of overfilled bags is higher than 0.15.:

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Alternative hypothesis: $p > 0.15$

The statistic for this case is:

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And replacing the info given we got:

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Nataly_w [17]

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