CAT 1999 — DILR Question 17
Directions: Each question has a set of four statements. Each statement has three segments. Choose the alternative where the third segment in the statement can be logically deduced using both the preceding two, but not just from one of them.
A. Dinosaurs are prehistoric creatures. Water-buffaloes are not dinosaurs. Water-buffaloes are not
prehistoric creatures.
B. All politicians are frank. No frank people are crocodiles. No crocodiles are politicians.
C. No diamond is quartz. No opal is quartz. Diamonds are opals.
D. All monkeys like bananas. Some GI Joes like bananas. Some GI Joes are monkeys.
Answer & solution
- A
C only
- B
B only
A and D
- D
B and C
(b) B only is the correct answer choice.
Statement A is invalid, as ‘No WB are PC’ cannot be validly concluded. What can, however, be validly concluded is that ‘Some PC (which are all D in shaded position) are not WB’.
D = Dinosaurs
PC = Prehistoric creatures
WB = Water buffaloes
Statement B is valid as evident from the Venn diagram
F = Frank creatures
P = Politicians
C = Crocodiles
P is a subset of F.
F and C are disjoint sets.
As the main set F can never intersect with C, the subset D will also never intersect or coincide with C.
Statement C is invalid: No valid conclusion can follow from two negative premises, as negatives have the
effect of separating one term from the others.
Statement D is invalid, as the ‘Some GI Joes’ who like bananas need not be monkeys.