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insens350 [35]
3 years ago
10

A simple random sample is free from any systematic tendency to differ from the population from which it was drawn.

Mathematics
1 answer:
Ket [755]3 years ago
4 0

Answer:

Pretty sure that it is False

Step-by-step explanation:

Sampling variation, random samples dont really reflect the population from where i is drawn, but it is close.

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A survey of 76 commercial airline flights of under 2 hours resulted in a sample average late time for a flight of 2.55 minutes.
nika2105 [10]

Answer:

The best point of estimate for the true mean is:

\hat \mu = \bar X = 2.55

2.55-1.96\frac{12}{\sqrt{76}}=-0.148    

2.55+1.96\frac{12}{\sqrt{76}}=5.248    

Since the time can't be negative a good approximation for the confidence interval would be (0,5.248) minutes. The interval are tellling to us that at 95% of confidence the average late time is lower than 5.248 minutes.

Step-by-step explanation:

Information given

\bar X=2.55 represent the sample mean for the late time for a flight

\mu population mean

\sigma=12 represent the population deviation

n=76 represent the sample size  

Confidence interval

The best point of estimate for the true mean is:

\hat \mu = \bar X = 2.55

The confidence interval for the true mean is given by:

\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}   (1)

The Confidence level given is 0.95 or 95%, th significance would be \alpha=0.05 and \alpha/2 =0.025. If we look in the normal distribution a quantile that accumulates 0.025 of the area on each tail we got z_{\alpha/2}=1.96

Replacing we got:

2.55-1.96\frac{12}{\sqrt{76}}=-0.148    

2.55+1.96\frac{12}{\sqrt{76}}=5.248    

Since the time can't be negative a good approximation for the confidence interval would be (0,5.248) minutes. The interval are tellling to us that at 95% of confidence the average late time is lower than 5.248 minutes.

7 0
3 years ago
The quotient of (x⁴+ 5x³ 3x - 15) and (x³ - 3) is a polynomial. What is the quotient?
lesya [120]

Answer:

x+5 (under assumption you meant to do -3x

Step-by-step explanation:

you can use long division.

Take the leading coefficient x^4 and divide it by x^3. This results in x which is going to be the first part of you quotient. Now take that x and multiply it by the divisor (x^3 - 3). This gives you x(x^3 - 3) = x^4 - 3x. Now subtract that x^4 - 3x from the original polynomial and repeat this until you can't divide anymore

x^4+5x^3-3x-15 - (x^4-3x) = 5x^3-15\\x^3/5x^3=5\\5(x^3-3) = 5x^3-15\\5x^3-15-(5x^3-15) = 0\\\\x+5

6 0
2 years ago
Random sample size of 81 are taken from an infinite population whose mean and standard deviation are 200 and 18, respectively. T
Ugo [173]

Answer:

the  mean and standard error of the mean are 200 and 2 respectively.

Step-by-step explanation:

Given that ;

the sample size n = 81

population mean μ = 200

standard deviation of the infinite population σ = 18

A population  is the whole set of values, or individuals you are interested in, from an experimental study.

The value of population characteristics such as the  Population mean (μ), standard deviation (σ) are said to be known as the population distribution.

From the given information above;

The sample size is large and hence based on the central limit theorem the mean of all the means is same as the population mean 200.

i.e

\mu = \bar \mu_x = 200

∴ The mean = 200

and the standard error of the mean can be determined via the relation:

\mathbf{standard \ error \ of \ mean = \dfrac{\sigma}{\sqrt {n}}}

\mathbf{standard \ error \ of \ mean = \dfrac{18}{\sqrt {81}}}

\mathbf{standard \ error \ of \ mean = \dfrac{18}{9}}

\mathbf{standard \ error \ of \ mean =2}

Therefore ; the  mean and standard error of the mean are 200 and 2 respectively.

6 0
3 years ago
Kate wants to buy some daisies for $6.99, some potting soil for $3.98, and a ceramic pot for $7.95. She has $20.00.Which number
trapecia [35]

Given:

Kate wants to buy some daisies for $6.99, some potting soil for $3.98, and a ceramic pot for $7.95. She has $20.00

Required:

Amount of change Kate receives back?

Explanation:

We will add each expense

6.99+3.98+7.95=18.92

Now, amount of change Kate receives back is 20.00 - 18.92 = 1.08

Answer:

Hence, amount of change Kate receives back is 1.08

8 0
1 year ago
Solve the following word problem.
gayaneshka [121]

Answer:

10$ per hour

Step-by-step explanation:

if she spended 120$ and had 180$ left, that means she had 300$ in the first place. of she works 30 hours, that means:

300 (the money she has)

÷ 30 ( her work hours )

When we divide this, the answer is ten. that is why she earns 10$ per hour

8 0
3 years ago
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