SAT Math Multiple Choice Practice Question 74: Answer and Explanation

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Question: 74

8. Sean claims that every number is either prime or the product of two primes. Which number could Vickie use to disprove Sean's statement?

A. 2
B. 10
C. 15
D. 18
E. 57

Correct Answer: D

Explanation:

D. The number 2 is prime, and 10 = 2 × 5, 15 = 3 × 5, and 57 = 3 × 19. Each of these numbers is the product of two primes. But 18 = 2 × 9 or 3 × 6, and neither 9 nor 6 is prime.

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