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miv72 [106K]
4 years ago
12

Please help #12 10 points

Mathematics
1 answer:
eimsori [14]4 years ago
3 0
1. add 40 to the 40 and 25
2. now you have
\frac{5x {}^{2} }{5}   = \frac{65}{5}
3. then you have
{x}^{2}  = 13
4. then square root
{x}^{2}  = 13
5.then round answer to nearest tenth which is
x = 3.61
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The water works commission needs to know the mean household usage of water by the residents of a small town in gallons per day.
valina [46]

Answer:

A sample of 179 is needed.

Step-by-step explanation:

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 - 0.85}{2} = 0.075

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

That is z with a pvalue of 1 - 0.075 = 0.925, so Z = 1.44.

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 previous study found that for an average family the variance is 1.69 gallon?

This means that \sigma = \sqrt{1.69} = 1.3

If they are using a 85% level of confidence, how large of a sample is required to estimate the mean usage of water?

A sample of n is needed, and n is found for M = 0.14. So

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

0.14 = 1.44\frac{1.3}{\sqrt{n}}

0.14\sqrt{n} = 1.44*1.3

\sqrt{n} = \frac{1.44*1.3}{0.14}

(\sqrt{n})^2 = (\frac{1.44*1.3}{0.14})^2

n = 178.8

Rounding up

A sample of 179 is needed.

7 0
3 years ago
I need help setting up the equations
Ilya [14]

Answer:

Just multiply the number by the percentage.

Step-by-step explanation:

1. Make the percentage into a decimal (%50= 0.50)

2. Multiply the decimal by the number.

8 0
2 years ago
Read 2 more answers
Show step by step work ​
SOVA2 [1]

Answer:

$60

Step-by-step explanation:

Movieland is in yellow....at the far left the Moviland- yellow 'regular' price for a DVD is shown as   y= $20

three of these would be  3 x $20 = $60

3 0
2 years ago
2(x−4)+3x=7 solve for x
sesenic [268]

Answer:

x = 3

Step-by-step explanation:

5x - 8 + 8 = 7 + 8

5x = 15

5x/5 = 15/5

15 divided by 5 equals 3

Hope this helped you out :)

7 0
3 years ago
Read 2 more answers
Pls help me tysm if you can!!
Mice21 [21]
The answer is 0.687.
8 0
3 years ago
Read 2 more answers
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