Self-study
If a motor is sound-insulated, then it is quiet enough to use in home appliances. ██ █ █████ ██ █████ ██████ ██ ███ ██ ████ ███████████ ████ ██ ███ ██ ████ ██ █████████████ █████████ ████ ██ ███ ██████ ████████████ ██ ██ ██████████ ███ █████ ██████ ██ ███ ██ ████ ███████████
Summary
The stimulus can be diagrammed as follows:
Notable Valid Inferences
If a motor is sound-insulated, it can be used in institutional settings.
No motors manufactured by EM Industries are sound-insulated.
Some motors that can be used in institutional settings are not manufactured by EM Industries.
17.
If the statements above are █████ █████ ███ ██ ███ █████████ ████ ██ █████
a
If a motor ███ ██ ████ ██ █████████████ █████████ ████ ██ ██ ████████████████
Could be false. While we know that every sound-insulated motor can be used in institutional settings, we do not know whether every motor that can be used in institutional settings is sound-insulated. (A) confuses the necessary and sufficient conditions.
b
None of the ██████ ████████████ ██ ██ ██████████ ███ ████████████████
Must be true. As shown below, by chaining the conditional claims, we see that “not made by EM Industries” is a necessary condition of “sound-insulated”.
c
At least some ██ ███ ██████ ████████████ ██ ██ ██████████ ███ ██ ████ ██ █████████████ █████████
Could be false. We know that some of the motors manufactured by EM Industries can’t be used in institutional settings, and it’s quite possible that all of them can’t!
d
If a motor ██ █████ ██████ ██ ███ ██ ████ ███████████ ████ ██ ██ ████████████████
Could be false. While we know that every sound-insulated motor is quiet enough to use in home appliances, we do not know whether every motor quiet enough for home appliances is sound-insulated. (D) confuses the necessary and sufficient conditions.
e
None of the ██████ ████████████ ██ ██ ██████████ ███ ██ ████ ██ █████████████ █████████
Could be false. We know that some of the motors manufactured by EM Industries can’t be used in institutional settings, but it’s possible that some can. There might be sufficient conditions for institutional use other than sound-insulation.