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Subject Test Math 1

Question 26 of 32

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SAT Subject Test

The numbers 3, 5, and 7 are three consecutive odd numbers that are prime. How many other triplets of consecutive odd numbers greater than 1 consist entirely of primes?

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None

Correct Answer: 
Yes

One

Correct Answer: 
No

Two

Correct Answer: 
No

Three

Correct Answer: 
No

More than three

Correct Answer: 
No

You can look at some triplets of consecutive odd numbers greater than 1:

5, 7, 9

11, 13, 15

25, 27, 29

53, 55, 57

93, 95, 97

You should quickly observe that any triplet of consecutive odd numbers would have one multiple of 3. (The numbers that are multiples of 3 are bolded and underlined.) Therefore, the only triplet of consecutive odd numbers greater than 1 that contains all primes is 3, 5, 7. The correct answer is (A).

Question Difficulty: 
hard