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3 years ago

Solve.

Mathematics

1 answer:

yarga [219]3 years ago

5 0

- 3/5x + 15 > 720
- 3/5x > 705
X < -423

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Gary needs 24 screws for every 2 chairs he builds

kicyunya [14]

Answer:

ok sooo is there something you need to be figured out orr are you just saying

Step-by-step explanation:

7 0

3 years ago

A population is estimated to have a standard deviation of 9. We want to estimate the population mean within 2, with a 99% level

cupoosta [38]

Answer:

The sample required is $n = 135$

Step-by-step explanation:

From the question we are told that

The standard deviation is $\sigma = 9$

The margin of error is $E = 2$

Given that the confidence level is 99% then the level of significance is mathematically evaluated as

$\alpha = 100-99$

$\alpha = 1 \%$

$\alpha = 0.01$

Next we will obtain the critical value $\frac{\alpha }{2}$ from the normal distribution table(reference math dot armstrong dot edu) , the value is

$Z_{\frac{\alpha }{2} } = Z_{\frac{0.05 }{2} } = 2.58$

The sample size is mathematically represented as

$n = [ \frac{Z_{\frac{\alpha }{2} } * \sigma }{E} ]^2$

substituting values

$n = [ \frac{ 2.58 * 9 }{2} ]^2$

$n = 135$

3 0

2 years ago

Find the population mean or sample mean as indicated. Sample: 19, 15, 6, 11, 24 Compute the sample mean for this data set. Selec

yKpoI14uk [10]

Answer:

$\overline{x}=15$

Step-by-step explanation:

the mean is given by:

$\overline{x} = \dfrac{\sum\limits_{i=1}^n x_i}{n} \quad\text{or}\quad \dfrac{\text{sum of all items}}{\text{number of items}}$

In our case this is:

$\overline{x} = \dfrac{19+15+6+11+24}{5} \Rightarrow \dfrac{75}{5}\\\\\overline{x} = 15\\\\$

side note: the main difference between sample mean and population mean is in the 'context'. However, the method to calculate them is the same.

By context I mean: if this the items are taken from some larger category for example: the ages of a few 'students' from a 'class'. Here 'students' are the sample from a larger set that is 'class'. The mean of the 'few students' will be called sample mean. In contrast, if we take the mean of the ages of the whole class then this is called population mean. (population mean == mean of the whole set)

In our case we aren't told exactly where these numbers come from, is this the whole set or a sample from it, the lack of context allows us to assume that the mean can either be population mean or sample mean. So we can safely use any symbol $\mu$ or $\overline{x}$ .