Self-study
Mayor: To keep our neighborhoods clean, every street in town will be swept at least once a month. ██ █ ████████████ █████ ████ ████████ ██████████ ███ ██ █████████ ████ ████ █████ ████████████ ███ ████████ ████ ████████████ ████ ██ █████████ ███ ███████ ██████████ ███ ████████ ███ ███████ █████████ ████ █████████ █████████████ ████ ██ █████████ ████████████
Summary
Every street in town will be swept at least once a month.
If a neighborhood needs to be swept more frequently than once a month, that neighborhood will be qualified for interim sweepings.
All requests for interim sweepings from qualified neighborhoods will immediately be satisfied.
Notable Valid Inferences
If a qualified neighborhood requests interim sweepings, that neighborhood’s streets will be swept more than once a month.
If a neighborhood is excessively dirty from major construction, that neighborhood will be qualified to receive sweepings more frequently than once a month.
If a neighborhood with excessive dirt from major construction requests interim sweepings, that neighborhood’s streets will be swept more than once a month.
13.
If all of the mayor's ██████████ ███ █████ ████ █████ ███ ██ ███ █████████ ████ ████ ██ █████
a
All neighborhoods in █████ ████████████ ██ █████ ███ ███ █████████ ██████████████
Could be false. The stimulus states that a neighborhood is qualified if there is excessive dirt from major construction, not merely if there is any type of construction at all. Maybe minor construction does not lead to excessive dirt!
b
All qualified neighborhoods ████ ███ █████ ███████ █████ ████ ████ ████ █ ██████
Could be false. The stimulus does not say that qualified neighborhoods that do not request interim sweepings will receive such sweepings (but it also doesn’t say that they won’t). Maybe some qualified neighborhoods will not submit a request and thus will only be swept monthly!
c
No street will ██ █████ ████ ████ ████ █ █████ ██████ ██ ██ ███████ ██ █ █████████ █████████████
Could be false. The stimulus doesn’t state that being a qualified neighborhood is the only way to receive more frequent sweepings. As far as we know, “qualified neighborhood that requests interim sweepings” is a sufficient, not necessary, condition of receiving interim sweepings.
d
A qualified neighborhood ████ ████████ ██ ███████ ████████ ████ ████ ███ ███████ █████ ████ ████ ████ █ ██████
Must be true. If a neighborhood is qualified for interim sweepings and it requests such sweepings, that request will be satisfied. In other words, that neighborhood will have its streets swept more than once a month!
e
No street in ██ ███████████ ████████████ ████ ██ █████ ████ ████ ████ █ █████ ████ ██ ███ ████████████ ████████ ███
Could be false. The stimulus doesn’t state that being a qualified neighborhood is the only way to receive more frequent sweepings. As far as we know, “qualified neighborhood that requests interim sweepings” is a sufficient, not necessary, condition of receiving interim sweepings.