Download Statistics Name_________________________ 1. A sample of

Statistics
Name_________________________
1. A sample of underweight babies was fed a special diet and the following weight gains.
They were observed at the end of three months.
6.7
2.7
2.5
3.6
3.4
4.1
4.8
5.9
8.3
a. Find the mean.
b. Find the standard deviation.
c. Make a boxplot.
d. If I add 5 to each, what is the mean? Median? Standard Deviation?
e. If I multiply each by 5, what is the mean? Median? Standard Deviation?
2. Suppose a frequency distribution is skewed with a median of $75 and a mode of $80.
which of the following is a possible value for the mean of the distribution.
a. $86
b. $91
c. $64
d. $75
e. None of these
3. The term tests scores of 15 students enrolled in Statistics class were recorded in
ascending order as follows:
4, 7, 7, 9, 10, 11, 13, 15, 15, 15, 17, 17, 19, 19, 20
After calculating the mean, median, and mode, an error is discovered: one of the 15’s is
really 17. the measures of central tendency which will change are:
a. the mean only
b. the mode only
c. the median only
d. the mean and mode
e. all three measures
4. The following shows reaction times for two different stimuli. If your reaction time is 4
seconds for the 1st stimulus and 1.8 seconds for the 2nd stimulus, which one do you react to
more quickly?
Mean
St. Dev
Stimulant #1
6
1.2
Stimulant #2
3.6
0.8
5. A random sample of 40 smoking people is classified in the following table:
Ages Frequency
10 - 20
4
20 - 30
6
30 - 40
12
40 - 50
10
50 - 60
8
a. Find the mean.
b. Find the Median.
c. Find the 80th percentile.
6. Which set of data has the smallest standard deviation?(No Calculator!)
a. 1, 1, 2, 3, 3
b. 5, 5, 5, 5, 5
c. 1, 2, 2, 2, 3
d. 1, 2, 3, 4, 5
e. 1, 1, 3, 5, 5
7. If the manager of a certain store decides to raise all prices by 20%, which of the
following values does not change?
a. mean
b. median
c. mode
d. standard deviation
e. all of these values change
8. What fraction of the population lies between 9 and 21 if the mean equals 15 and the
standard deviation is 3?
9. If you remove the outliers what will happen to the following.
a. mean
b. median
c. range
d. Interquartile range
e. variance
10. A teacher has two American History classes. The morning class has 15 students and the
average on the first test was 84. The afternoon class has 25 students and their average
on the same test was 72. If the teacher combines the scores from the two classes, what
is the average score?
11. If you are told that a population has a mean of 15 and a variance of 0, what must be true?
12. If the maximum value of a data set with ten values is increased by 25, what will happen
to the median?