Consider the statement: 'No number in the set is prime.' Which of the following is its negation?
Answer and explanation
Correct answer: C. Some number in the set is prime
- Step 1: 'No number is prime' means 'for every number , is not prime'.
- Step 2: Its negation is 'there is a number that is prime', i.e. some number in the set is prime (at least one).
Answer
Some number in the set is prime.
Why not the others: 'Every number is prime' is far too strong; 'some number is not prime' is compatible with the original; 'exactly one' is only one way in which the original can fail; 'no number in the set is composite' is about a different property.
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