1-A company has developed a new battery, but the average lifetime of all of the batteries it makes is unknown. In order to estimate this average, a sample of 500 batteries is tested and the average lifetime of this sample is found to be 225 hours. The 225 hours is the value of a:

Group of answer choices:

parameter

sample

population

statistic

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2-Which of the following describes the relationship between parameters and statistics?

Group of answer choices:

We use parameters to estimate or test statistics

Statistics and parameters are the same thing

We use statistics to estimate or test parameters

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3-If X has a normal distribution, which of the following is true about the shape (distribution) of the random variable X-bar?

Group of answer choices:

X-bar is exactly normal if n > 30

X-bar is exactly normal for any n

X-bar is approximately normal if n > 30

X-bar is approximately normal for any n

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4-If X does not have a normal distribution, which of the following is true about the shape (distribution) of the random variable X-bar?

Group of answer choices:

X-bar is approximately normal if n > 30

X-bar is approximately normal for any n

X-baris exactly normal if n > 30

X-bar is exactly normal for any n

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5-Which of the following is true about the standard error of the random variable X-baras n increases?

Group of answer choices:

The standard error of X-barstays the same.

Not enough information to tell.

The standard error of X-bardecreases.

The standard error of X-barincreases.

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6-Which of the following is true about the mean of the random variableX-baras n increases?

Group of answer choices:

The mean of X-barstays the same

The mean of X-barincreases

Not enough information to tell

The mean of X-bar decreases

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7-What is the symbol we use to represent the mean of the random variable X-bar?

Group of answer choices:

Mu with subscript X

Capital X-bar

Mu with subscript X-bar

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8- The set of all possible sample means from all possible samples of size n from the population is known as the:

Group of answer choices:

Sampling distribution of X-bar

Not enough information to tell

Population probability distribution of X

Sample mean of the population of X

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9-How large does n generally have to be in order for the Central Limit Theorem to take effect? (Assume Xdoes not have a normal distribution.)

Group of answer choices:

np at least 10 and n(1-p) at least 10

np 10

n > 30

n can be any value

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10-The Central Limit theorem tells us important results that pertain to:

Group of answer choices:

The standard error of the distribution of X-bar

The mean of the distribution of X-bar

The shape (type) of the distribution of X-bar

Allof the above

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