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3 years ago

What is a expression equivalent to 9-(-12)

Mathematics

1 answer:

swat323 years ago

3 0

Answer:

9 + 12

Step-by-step explanation:

Two negative signs together makes addition!

Hope this helps!

- doomdabomb

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There are 2,000 eligible voters in a precinct. A total of 500 voters are randomly selected and asked whether they plan to vote f

Ann [662]

Answer:

$0.7 - 2.58 \sqrt{\frac{0.7(1-0.7)}{500}}=0.647$

$0.7 + 2.58 \sqrt{\frac{0.7(1-0.7)}{500}}=0.753$

And the 99% confidence interval would be given (0.647;0.753).

So the correct answer would be:

a. 0.647 and 0.753

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".

The population proportion have the following distribution

$p \sim N(p,\sqrt{\frac{p(1-p)}{n}})$

Solution to the problem

The estimated population proportion for this case is:

$\hat p = \frac{350}{500}=0.7$

The confidence interval would be given by this formula

$\hat p \pm z_{\alpha/2} \sqrt{\frac{\hat p(1-\hat p)}{n}}$

For the 99% confidence interval the value of $\alpha=1-0.99=0.01$ and $\alpha/2=0.005$ , with that value we can find the quantile required for the interval in the normal standard distribution.

$z_{\alpha/2}=2.58$

And replacing into the confidence interval formula we got:

$0.7 - 2.58 \sqrt{\frac{0.7(1-0.7)}{500}}=0.647$

$0.7 + 2.58 \sqrt{\frac{0.7(1-0.7)}{500}}=0.753$

And the 99% confidence interval would be given (0.647;0.753).

So the correct answer would be:

a. 0.647 and 0.753

7 0

3 years ago

Ella collects 50 bottles to recycle. Of the bottles she collects, 19 are plastic and the rest are glass.

nekit [7.7K]

QUESTION A

The total number of bottles Ella collected is
$50$

The number of bottles that are plastic is

$19$

The percentage of bottles that are plastic is

$= \frac{number \: of \: plastic \: bottles}{total \: number \: of \: bottes} \times 100\%$

$= \frac{19}{50} \times 100\%$

$= 19 \times 2\%$
$= 38\%$

Therefore 38% of the bottles are plastic.

QUESTION B

The total number of bottles that are glass is
$50 - 19 = 31$

The total number of bottles Ella collected is
$50$

The percentage of bottles that is glass is
$= \frac{number \: of \: glass \: bottles}{total \: number \: of \: bottles} \times 100\%$

$= \frac{31}{50} \times 100\%$

$= 31 \times 2\%$
$= 62\%$

Therefore 62% of the bottles are glass

8 0

3 years ago

What is the percent decline, to the nearest whole number, of rusty patched bumble bees from 20 years ago to today?

Andrej [43]

Sasuke is pretty cool

6 0

3 years ago

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Theorem 8.9 : The line segment joining the mid-points of two sides of a triangle is parallel to the third side.

Alla [95]

Answer:

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