[pg141]10. Umbrellas are useful on a journey;
What is useless on a journey should be left behind.
Univ. is “things”; m = useful on a journey; x = umbrellas; y = things that should be left behind.
All x are m; All m′ are y. | ∴ Some x′ are y. |
i.e. Some things, that are not umbrellas, should be left behind on a journey.
11. Audible music causes vibration in the air;
Inaudible music is not worth paying for.
Univ. is “music”; m = audible; x = music that causes vibration in the air; y = worth paying for.
All m are x; All m′ are y′. | ∴ No x′ are y. |
i.e. No music is worth paying for, unless it causes vibration in the air.
12. Some holidays are rainy;
Rainy days are tiresome.
Univ. is “days”; m = rainy; x = holidays; y = tiresome.