The difference of a number and 9 <br><br> •write as a algebraic expression

Oliver and layla each built a rectangular prism with centimeter cubes. Both prisms have a volume of 24 cubic centimeters, but th

Nadusha1986 [10]

The volume of a rectangular prism is width×length×width. With the given volume of 24 you could find 2 ways with different sets of numbers that multiply into 24.

Oliver's= 6, 2, 2
Layla, 3, 2, 4

4 0

3 years ago

How to work out an angle using cosine. three sides are; 8,19,12.

Kay [80]

To solve for cos use
adjacent over hypotenuse
divide the lengths of the sides
adj. / hyp.

7 0

3 years ago

A= 1/2bh pls help I don’t remember how to do this

marta [7]

I think it’s the triangle

8 0

3 years ago

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Rory is staying in a cabin on a hill 300 feet above sea level. She walks down the hill to the water’s edge. The equation of her

Tatiana [17]

<span>The equation is e = 300 - 10t. t is greater or equal than 0 and given that e cannot be negative, 300 - 10 t greaetr or equal than 0 => 10 t greater or equal than 300, and t greater or equal than 300/10 = 30. This is the viable points are times from 0 to 10 and elevation from 300 to 0. Some points are (0,300) which is the initial point (when Rory is on the top); (1, 290); (2, 280); (3, 270); (4, 260); (5, 250); (6, 240); (10, 200), (20, 100), (30, 0).</span>

7 0

3 years ago

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Customers arrive at a movie theater at the advertised movie time only to find that they have to sit through several previews and

Naddika [18.5K]

Answer:

Using a 90% confidence level

A. A sample size of 68 should be used.

B. A sample size of 98 should be used.

Step-by-step explanation:

I think there was a small typing mistake and the confidence level was left out. I will use a 90% confidence level.

We have that to find our $\alpha$ level, that is the subtraction of 1 by the confidence interval divided by 2. So:

$\alpha = \frac{1-0.9}{2} = 0.05$

Now, we have to find z in the Ztable as such z has a pvalue of $1-\alpha$ .

So it is z with a pvalue of $1-0.05 = 0.95$ , so $z = 1.645$

Now, find the margin of error M as such

$M = z*\frac{\sigma}{\sqrt{n}}$

In which $\sigma$ is the standard deviation of the population and n is the size of the sample.

A. If we want to estimate the population mean time for previews at movie theaters with a margin of error of 72 seconds, what sample size should be used?

We have the standard deviation in minutes, so the margin of error should be in minutes.

72 seconds is 72/60 = 1.2 minutes.

So we need a sample size of n, and n is found when M = 1.2. We have that $\sigma = 6$ . So

$M = z*\frac{\sigma}{\sqrt{n}}$

$1.2 = 1.645*\frac{6}{\sqrt{n}}$

$1.2\sqrt{n} = 6*1.645$

$\sqrt{n} = \frac{6*1.645}{1.2}$

$(\sqrt{n})^{2} = (\frac{6*1.645}{1.2})^{2}$

$n = 67.65$

Rounding up.

A sample size of 68 should be used.

B. If we want to estimate the population mean time for previews at movie theaters with a margin of error of 1 minute, what sample size should be used?

Same logic as above, just use M = 1.

$M = z*\frac{\sigma}{\sqrt{n}}$

$1 = 1.645*\frac{6}{\sqrt{n}}$