The sum of 7 consecutive natural numbers is 1617. Find how many of these are prime numbers.
A2 ✓ Correct
B3
C1
D4
Correct answer: (A) 2
Explanation
Only 2 of the seven numbers are prime.
Sum of 7 consecutive numbers = 7 x middle number = 1617.
Middle number = 1617/7 = 231, so numbers run 228 to 234.
Even numbers 228, 230, 232, 234 are not prime; 231 = 3 x 7 x 11.
Only 229 and 233 are prime.
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