Week 2 Quiz

The Palmer penguins field log records each bird's species: Adelie, Chinstrap, or Gentoo. What kind of variable is species, and which kind of graph fits it?

Select one.

• Categorical, so a bar chart or a pie chart fits it
• Quantitative, so a histogram with equal-width bins fits it
• Quantitative, so a dot plot above a number line fits it
• Categorical, so a histogram with touching bars fits it

The field log counts 152 Adelie, 68 Chinstrap, and 124 Gentoo penguins, for n = 344 in all. What is the relative frequency of Chinstrap penguins, as a percentage rounded to one decimal? Enter the number only.

Type a short answer.

A campus survey asks students which of five streaming services they use and tells them to check all that apply. The reported percentages add up to well over 100%. Which graph is the honest choice for these results?

Select one.

• A pie chart, because the results are percentages
• A histogram, because the services are counted in bins
• A bar chart, because one student can fall in several categories
• A stem plot, because it keeps every student's answer

A dot plot of the 12 month lengths of a common year shows 1 dot at 28 days, 4 dots at 30 days, and 7 dots at 31 days. Which description of its shape is correct?

Select one.

• Right-skewed, because most of the dots pile up on the right
• Left-skewed, because the thin tail stretches left toward 28
• Symmetric, because the dots are spread over only a few values
• Bimodal, because the dots form two separate stacks

A histogram of the 342 penguin body masses has its main pile in the middle bins and a long, thinning tail of heavy birds. The middle value is 4,050 g, and the average is 4,201.75 g. Which conclusion fits this evidence?

Select one.

• Left-skewed, because the average is the larger of the two numbers
• Symmetric, because the average and the middle value are both near 4,000 g
• Bimodal, because the average and the middle value are different
• Mildly right-skewed, because the average sits above the middle value

Which statements describe a histogram but not a bar chart? Select all that apply.

Select every option that applies.

• Its bars touch, because they cover neighboring ranges of one number line
• Its bars can be listed in any order without changing the picture
• Its bins all share the same width
• Gaps between its bars show that the groups are separate categories
• Its bars must stay in number-line order

Read the two-way table below.

How many penguins in all were logged on Dream? Enter a whole number.

Type a short answer.

A bar chart of month lengths starts its vertical axis at 27 days, so February's bar is drawn 1 unit tall and a 31-day month's bar is drawn 4 units tall. Which statement is accurate?

Select one.

• February has about 90.3% as many days, so the chart exaggerates a 3-day gap
• February really has about a quarter as many days as a 31-day month
• The chart is accurate, because each bar's height is measured correctly from 27
• The chart misleads only because its bars are not touching

The 12 month lengths of a common year form a whole population, so the right letter for their count is N = 12, not n = 12.

True or false.

• True
• False

A stem plot of the 12 month lengths uses the tens digit as the stem. Stem 2 holds the single leaf 8, and stem 3 holds the leaves 0 0 0 0 1 1 1 1 1 1 1. How many months have 31 days?

Select one.

• 4
• 11
• 7
• 31