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4 years ago

Instructions: Complete each question by choosing or typing in the best answer.

Mathematics

1 answer:

kupik [55]4 years ago

5 0

The sum of 38 and twice a number x is 124. The value of "x" is 43

- 2x - 5 is equal to – 91.

Solution:

Given that , The sum of 38 and twice a number x is 124.

We have to find what is - 2x - 5?

Now, according to given information, 38 + 2 × x = 124

2x + 38 = 124

2x = 124 – 38

2x = 86

x = 43

So, the value of x is 43

Now, Evaluating - 2x – 5

Substitute "x" = 43 to evaluate

- 2(43) – 5

- 86 – 5 = - 91

Hence, the required answer is – 91.

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State University uses thousands of fluorescent light bulbs each year. The brand of bulb it currently uses has a mean life of 600

Ipatiy [6.2K]

Answer:

The test statistic is t = 2.5.

The p-value of the test is of 0.007 < 0.05, which means that the evidence supports the manufacturer's claim at the .05 significance level.

Step-by-step explanation:

Mean life of 600 hours. Test if it is more.

At the null hypothesis, we test if the mean is of 600 hours, that is:

$H_0: \mu = 600$

At the alternative hypothesis, we test if the mean is of more than 600 hours, that is:

$H_1: \mu > 600$

The test statistic is:

$t = \frac{X - \mu}{\frac{s}{\sqrt{n}}}$

In which X is the sample mean, $\mu$ is the value tested at the null hypothesis, s is the standard deviation and n is the size of the sample.

600 is tested at the null hypothesis:

This means that $\mu = 600$

Suppose 100 bulbs were tested and found to have a mean of 625 hours with a standard deviation of 100.

This means that $n = 100, X = 625, s = 100$ .

Value of the test-statistic:

$t = \frac{X - \mu}{\frac{s}{\sqrt{n}}}$

$t = \frac{625 - 600}{\frac{100}{\sqrt{100}}}$

$t = 2.5$

The test statistic is t = 2.5.

P-value of the test and decision:

The p-value of the test is the probability of finding a sample mean above 625 hours, which is a right-tailed test, with t = 2.5 and 100 - 1 = 99 degrees of freedom.

Using a t-distribution calculator, this p-value is of 0.007.

The p-value of the test is of 0.007 < 0.05, which means that the evidence supports the manufacturer's claim at the .05 significance level.

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3 years ago

Can some one give me a step by step with all the work and answer ??? 8n + 7 = 31

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I presume you're trying to find n, so first remove the 7 from each side.

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4 years ago

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Answer:

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