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mihalych1998 [28]
3 years ago
15

A study has indicated that the sample size necessary to estimate the average electricity use by residential customers of a large

western utility company is 900 customers. Assuming that the margin of error associated with the estimate will be ±30 watts and the confidence level is stated to be 90 percent, what was the value for the population standard deviation?
Mathematics
1 answer:
Zanzabum3 years ago
7 0

Answer:

\sigma=547.1125

Step-by-step explanation:

-The margin of error is calculated using the formula:

ME=z_{\alpha/2}\times \frac{\sigma}{\sqrt{n}}\\\\

-We substitute the values, n=900 and ME=30 in the formula to solve for standard deviation:

ME=z_{\alpha/2}\times \frac{\sigma}{\sqrt{n}}\\\\\\30=1.645\times\frac{\sigma}{\sqrt{900}}\\\\\sigma=\frac{30^2}{1.645}\\\\=547.1125

Hence, the population standard deviation is 547.1125

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hodyreva [135]

We need to find the expression for " number_of_prizes is divisible number_of_participants". Also there should not remain any remainder left. On in order words, we can say the reaminder we get after division is 0.

Let us assume number of Prizes are = p and

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If we divide number of Prizes by number of participants and there will be not remainder then there would be some quotient remaining and that quotent would be a whole number.

Let us assume that quotent is taken by q.

So, we can setup an expression now.

Let us rephrase the statement .

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In fraction form we can write

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3 years ago
Find all solutions in the interval [0, 2π). tan x + sec x = 1
svp [43]
Use the identity 
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- so sec x = sqrt(1 + tan^2 x) then:-
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sqrt ( 1 + tan^2 x) = 1 - tan x
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Hope this helps!

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inna [77]

Answer:

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Step-by-step explanation:

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You see that the absolute value returned the same value if the value was positive.

You see that the absolute value returned the opposite value if the value was negative.

You can include 0 in either.

Let's look at |x+3| alone for a second.

*|x+3|=x+3 if x+3 is positive or zero.

When is x+3 positive or zero? [greater than or equal to 0]

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Subtract 3 on both sides

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*|x+3|=-(x+3) if x+3 is negative or zero.

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So looking at the bullet points (the *), x>2 fits into the first inequality.

Therefore, |x+3|=x+3.

8 0
2 years ago
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