STT 231: Test 1 Questions with 100% Correct
Answers
You asked ten of your classmates about their weight. On the basis of this information,
you stated that the average weight of all students in your university or college is 142.6
pounds. This is an example of:
statistic
A company has developed a new battery, but the average lifetime is unknown. In order
to estimate this average, a sample of 100 batteries is tested and the average lifetime of
this sample is found to be 250 hours. Identify population, sample, variable, parameter,
and statistic.
-Population: all new batteries
-Sample: 100 tested batteries
-Variable: battery lifetime
-Parameter: average of all tested batteries
-Statistic: average of 250 hours
A recent Wall Street Journal poll asked a group of American voters to rate economic
conditions in the United States. 22% of the respondents rated economic conditions as
"favorable." Identify the population, sample, sample statistic, and population
parameter in this survey.
-Population: eligible voters
-Sample: chosen voters
-Statistic: 22% favorability of sample
-Parameter: Percentage of all voters who would consider the economy favorable
, Quantitative data
Naturally numbers, averages, height, weight, age, GPA, credit hours, etc.
Qualitative data
Not naturally numbered data, major, etc.
A recent study examined the intended travel destinations for a sample of residents from
Grand Rapids, Michigan. The respondents indicated the likely destination of their next
vacation. What are the units and variables?
-Units: people who responded
-Variables: intended travel destination
For a class the average score was 70, the median 63 and standard deviation 13. The
instructor decided to add 5 points to all the scores. How will the mean, median, and
standard deviation change?
-Mean and median will increase by 5 and standard deviation will not change.
When will the mean equal the median?
Symmetrical distribution
When will the mean be less than the median?
Skewed left (negatively skewed)
When will the mean be greater than the median?
Skewed right (positively skewed)
What pieces of information do we need to construct a box and whisker plot?
-Min, Q1, median, Q3, and max
Answers
You asked ten of your classmates about their weight. On the basis of this information,
you stated that the average weight of all students in your university or college is 142.6
pounds. This is an example of:
statistic
A company has developed a new battery, but the average lifetime is unknown. In order
to estimate this average, a sample of 100 batteries is tested and the average lifetime of
this sample is found to be 250 hours. Identify population, sample, variable, parameter,
and statistic.
-Population: all new batteries
-Sample: 100 tested batteries
-Variable: battery lifetime
-Parameter: average of all tested batteries
-Statistic: average of 250 hours
A recent Wall Street Journal poll asked a group of American voters to rate economic
conditions in the United States. 22% of the respondents rated economic conditions as
"favorable." Identify the population, sample, sample statistic, and population
parameter in this survey.
-Population: eligible voters
-Sample: chosen voters
-Statistic: 22% favorability of sample
-Parameter: Percentage of all voters who would consider the economy favorable
, Quantitative data
Naturally numbers, averages, height, weight, age, GPA, credit hours, etc.
Qualitative data
Not naturally numbered data, major, etc.
A recent study examined the intended travel destinations for a sample of residents from
Grand Rapids, Michigan. The respondents indicated the likely destination of their next
vacation. What are the units and variables?
-Units: people who responded
-Variables: intended travel destination
For a class the average score was 70, the median 63 and standard deviation 13. The
instructor decided to add 5 points to all the scores. How will the mean, median, and
standard deviation change?
-Mean and median will increase by 5 and standard deviation will not change.
When will the mean equal the median?
Symmetrical distribution
When will the mean be less than the median?
Skewed left (negatively skewed)
When will the mean be greater than the median?
Skewed right (positively skewed)
What pieces of information do we need to construct a box and whisker plot?
-Min, Q1, median, Q3, and max
