Week 3 Quiz

Penguin species (Adelie, Chinstrap, or Gentoo) is recorded for every bird in the Palmer field log. Which measure of center can describe this variable?

Select one.

• The mean, after coding the species as 1, 2, and 3
• The mode, because species is a nominal label
• The median, because the species can be listed in order
• The mean, because every bird has a species

The six faces of a fair die, 1 through 6, are every face there is, and their mean is 3.5. How should that 3.5 be described and written?

Select one.

• A parameter, written μ, because the faces are a whole population
• A statistic, written x̄, because it was computed from data
• A parameter, written x̄, because the faces are a whole population
• A statistic, written μ, because six values is a small sample

The twelve month lengths of a common year (31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 days) add to 365 days. What is their mean, in days, rounded to four decimals? Enter the number only.

Type a short answer.

The twelve month lengths, in calendar order, are 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 days. What is their median?

Select one.

• 30 days
• 30.5 days
• 31 days
• 30.4167 days

Someone types the six faces of a die into a spreadsheet as 1, 2, 3, 4, 5, 60, mistyping the 6 as 60. What are the mean and the median of the typed values?

Select one.

• Mean 3.5 and median 12.5
• Mean 12.5 and median 12.5
• Mean 3.5 and median 3.5
• Mean 12.5 and median 3.5

The 342 penguin body masses have a mean of 4,201.75 g and a median of 4,050 g. What does this comparison suggest about the shape of the distribution?

Select one.

• Right-skewed, because a tail of heavy birds pulls the mean above the median
• Left-skewed, because the mean is the larger of the two numbers
• Symmetric, because the mean and the median differ by less than 200 g
• Left-skewed, because most of the birds sit at the lighter end

Treat the numbers 1, 2, 3, 4, 5, 6 as a sample of six rolls of a die. Their mean is 3.5, and their squared deviations from the mean add to 17.5. What is the sample variance s²? Enter the number only.

Type a short answer.

For the 342 penguin body masses (a sample), a spreadsheet's STDEV.S returns about 801.95. A classmate wants to report the variance instead. What are the units of each number, and which one belongs in a report to a non-technical reader?

Select one.

• Both are in grams; report either one
• The standard deviation is in grams and the variance in square grams; report the standard deviation
• The standard deviation is in square grams and the variance in grams; report the variance
• Both are unitless; report the variance because it is larger

For the 342 penguin body masses, a spreadsheet's QUARTILE.INC returns Q1 = 3,550 g and Q3 = 4,750 g. Using those two values, what is the upper fence of the 1.5 × IQR rule, in grams? Enter the number only.

Type a short answer.

For the twelve month lengths, Q1 = 30 days and Q3 = 31 days, so the IQR is 1 day and the fences of the 1.5 × IQR rule are 28.5 and 32.5 days. Select every true statement.

Select every option that applies.

• February's 28 days is flagged as a potential outlier
• February should be deleted from the data because it is flagged
• February is a real calendar fact, so it stays in the data
• The seven 31-day months are flagged because 31 is the largest value
• No month lies above the upper fence of 32.5 days