Question

Read the statement.Rooney notices that the numbers 5,7,11,13,17,19 are all odd numbers and prime numbers. She makes the conjecture that all odd numbers are prime numbers.Which of the following are counterexamples to the statement? Select all that apply.

Answer 1

Hello!

She makes the conjecture that all odd numbers are prime numbers.

It is false, we have infinite counterexamples, let's analyze the alternatives and mark some:

• The number 21 is an odd number and not prime.

True, because 21 can be divided by: 1, 3, 7, 21.

• The number 9 is an odd number and not prime.

True, it can be divided by 1, 3, 9.

• The number 15 is an odd number and not prime.

True, it can be divided by: 1, 3, 5, 15.

• The number 23 is an odd number and is prime.

True, it's prime. BUT it isn't a counterexample, just an example as mentioned in the exercise.

Answer:

You'll select the alternatives: 1, 2 and 3.