Ch.4 Quiz

Which of the following is not a value used in a five-number-summary of a data set? the lowest value the mean the lower quartile the upper quartile

the mean

What is the value called that occupies the middle position when the data are ranked in order according to size? the sample variance the median the proportion the mean

the median

Fill in the blank. The _________ corresponding to a particular value tells us how many standard deviations the value is from the mean. z-score percentage mean proportion

z-score

What is the interquartile range of the age of seven kids randomly sampled at a local mall? The ages are 15, 18, 5, 10, 9, 12 and 13. 17.9 13 6 4.5

6

The number of horses owned by farmers in a small rural community was recorded as follows. 2, 6, 9, 10, 15. What is the sample mean? 8.40 2.16 4.83 9.0

8.40

Suppose a basketball team observed over ten games made the following number of free-throws in each game. What is the sample mean for these observations? Data: 2, 9, 15, 8, 7, 12, 11, 5, 18, 11. 11 10 9.5 9.8

9.8

According to the Empirical Rule, what percentage of the observations in a data set that can be reasonably approximated by a normal curve lie within two standard deviations of the mean? 95% 99% 68% 50%

95%

Which of the following is not true with regards to finding the median of a data set? If n is odd, the sample median is the single middle value of the ordered list. The first step is to order the data set from smallest to largest. If n is even the sample median is the average of the middle two values in the ordered list. Any repeated values should be removed from the data set prior to determining the median.

Any repeated values should be removed from the data set prior to determining the median.

Which of the following is used to describe the fact that for any number k≥1, at least 100(1-\frac{1}{k^2} )% of the observations in any data set are within k standard deviations of the mean? The rth percentile Chebyshev's Rule The z-score The Empirical Rule

Chebyshev's Rule

What can we say about a data point that has a z-score of -2.3? The data point is 2.3 standard deviations below the mean. The data point has a standard deviation equal to -2.3. The data point is equal to the mean minus 2.3. The data point is 2.3 standard deviations above the mean.

The data point is 2.3 standard deviations below the mean.

What is the value of sigma(x-mean) for any given set of data? cannot tell from the information given 1 0 mean

0

Suppose the distribution of children's ages at a local YMCA is approximately normal. What is the z-score for a child who is 10 years old if the distribution has a mean age of 9 and a standard deviation of 2? 0.71 -0.50 0.50 1

0.50

Suppose the weight loss over a three month period in patients is collected for a clinical study to determine the effects of a given weight loss medication. What is the median weight loss for the following sample of 6 patients? Sample data in pounds: 20, 10, 8, 10, 15, and 11. 9 10.5 11 12.3

10.5

If the sample standard deviation for the life of a sample of 48 batteries is 173, which of the following numbers is the variance for this set of data closest to? 29,929 86.5 13.2 173.1

29,929

What is the box width equal to when constructing a boxplot for a data set? It is equal to the interquartile range. It is equal to the median minus the lower quartile. It is equal to the difference between the largest value in the data set and the smallest value in the data set. It is equal to the upper quartile minus the median. It is not affected by extreme outliers.

It is equal to the interquartile range.

Which of the following is not affected by extreme outliers? Mean Trimmed Mean Median Variance

Median

Which of the following is a not a measure of variability? Proportion Population Variance Interquartile Range Standard Deviation

Proportion

Which of the following summary quantities are used for categorical data? Variance Median Proportion Mean

Proportion

Which of the following statements about sample standard deviations and sample variances is not true? The smaller the value of s2 or s, the larger the variability of the data set. The value of s is always great than or equal to zero. We compute the standard deviation s, which is the square root of the variance s2, in order to measure the variability in the same units as the original observations. If s2 or s is equal to zero, all the measurements must have the same value.

The smaller the value of s2 or s, the larger the variability of the data set.

With regards to the shape of a histogram, when are the mean and median equal? When the histogram is unimodal with a longer lower tail. When the histogram is symmetric. When the histogram is bimodal. When the histogram is unimodal with a longer upper tail.

When the histogram is symmetric.

If a sample has 200 observations and the researcher is interested in computing a 10% trimmed mean, how many observations will be removed from the sample before computing the mean? four observations forty observations ten observations twenty observations

forty observations

Which of the following is the average of all values in the entire population? trimmed mean population proportion sample mean population mean

population mean