Statistics Ch. 3 Extra Credit

Using the Empirical Rule, about what percent of the data is between 1 and 2 standard deviations below the mean?

13.5%

The standard deviation of a sample was reported to be 20. The report indicated that Σ(x-x̄)2 = 7200. What is the sample size?

19

The median of a sample will always equal the

50th percentile

A researcher has collected the following sample data. The mean of the sample is 5. 2, 2, 3, 5, 12

6

The empirical rule states that, for data having a bell-shaped distribution, the percentage of data values being within one standard deviation of the mean is approximately

68%

According to Chebychev's Rule, at least what percentage of the observations in any data set are contained within a distance of 2 standard deviations of the mean?

75%

The closing stock price of MNM Corporation for the last 7 trading days is shown below. The median is:

85

True/False: The larger the z-score, the farther the distance from the value to the median.

False

A researcher has collected the following sample data. 4, 5, 5, 5, 6, 6, 7, 8, 12, 12 The 75th percentile is:

8

True/False: In a set of numerical data, the value for Q2 is always halfway between Q1 and Q3.

False

The standard deviation of a sample was reported to be 20. The report indicated that Σ(x-x̄)2= 7200. What has been the sample size?

(20)^2= (square root of (7200 / n - 1)) 7200/400=n-118= n-1 n=19

The variance of a sample of 169 observations equals 576. The standard deviation of the sample equals

24

A researcher has collected the following sample data. The mean of the sample is 5. 2, 2, 3, 5, 12 The standard deviation is:

4.062

Which of the following is true about a right-skewed distribution?

The median is less than the mean.

True/False: Z-scores can be used to identify outliers.

True

A box plot is a graphical representation of data that is based on

a five number summary

If a data set has an even number of observations, the median

is the average value of the two middle items when all items are arranged in ascending order

The first quartile

is the same as the 25th percentile

The interquartile range is used as a measure of variability to overcome what difficulty of the range?

the range is influenced too much by extreme values

Since the median is the middle value of a data set it a. must always be smaller than the mean b. must always be larger than the mode c. must always be smaller than the mode d. None of these alternatives is correct.

d

The pth percentile is a value such that at least p percent of the observations are ____ and at least 100 - p percent of the observations are ___.

less than or equal to this value; greater than or equal to this value

In a five number summary, which of the following is not used for data summarization?

mean

Which of the following provides a measure of central location for the data?

mean

In computing the mean of a sample, the value of Σxi is divided by

n

Which of the following symbols represents the size of the sample

n

The numerical value of the standard deviation can never be

negative

The difference between the largest and the smallest data values is the

range

If index i (which is used to determine the location of the pth percentile) is not an integer, its value should be

rounded up

When n-1 is used in the denominator to compute variance,

the data set is a sample.

Consider the 5-number summary 2, 5, 10, 17, 38.The number 38 is

the highest value in the data set and an outlier.

In a box plot, data value x is considered an outlier if

x < Q1 - 1.5(IQR) or x > Q3 + 1.5(IQR).

Which of the following symbols represents the mean of the sample?

x̄

Which of the following symbols represents the mean of the population?

μ

Which of the following symbols represents the standard deviation of the population?

σ

Since the mode is the most frequently occurring data value, it

None of these alternatives is correct.