Inference selection – Radios sold and quality standard: Statements: (i) All radios sold in that shop are of high standard. (ii) Some Murphy radios are sold in that shop. Inferences to test: I) All high-standard radios are manufactured by Murphy. II) Some Murphy radios are of high standard. III) None of the Murphy radios is of high standard. IV) Some high-standard Murphy radios are sold in that shop.

Introduction / Context:
We combine a universal statement about items sold at a shop with a particular about a brand (Murphy) to decide which inferences necessarily hold.

Given Data / Assumptions:

• SoldInShop ⊆ HighStandard.
• Some Murphy ∩ SoldInShop (i.e., at least one Murphy radio is sold in the shop).

Concept / Approach:
Anything sold in the shop is high standard. Therefore those “some Murphy radios” that are sold there are high standard (II). Moreover, those same high-standard Murphy radios are indeed sold in the shop (IV). Inference I claims all high-standard radios are Murphy – an overreach. Inference III contradicts II.

Step-by-Step Solution:
From “Some Murphy are sold,” pick x ∈ Murphy ∩ SoldInShop.By the universal, x ∈ HighStandard.Hence “Some Murphy radios are of high standard” (II) and “Some high-standard Murphy radios are sold in that shop” (IV) both hold.

Verification / Alternative check:
No model can satisfy the premises and make II false; nor can it negate IV, since the specific x is both Murphy, high standard, and sold in that shop.

Why Other Options Are Wrong:
I is unsupported; III contradicts II.

Common Pitfalls:
Reversing subset directions or overlooking that “some” witnesses can be carried through universals.

Final Answer:
II and IV inferences only.