List all prime numbers between 30 and 50 inclusive.
2025
List all prime numbers between 30 and 50 inclusive.
- A.
31,37,41,43
- B.
31,37,43,47
- C.
31,37,41,43,46
- D.
31,37,41,43,47
Attempted by 2 students.
Show answer & explanation
Correct answer: D
Concept: A prime number is a natural number greater than 1 whose only positive divisors are 1 and itself. To find every prime within a range, test each number for divisibility by every prime not exceeding its square root — if none divide it, the number is prime.
Application: List the numbers from 30 to 50 and eliminate composite numbers systematically.
Remove every even number in the range (30, 32, 34, 36, 38, 40, 42, 44, 46, 48, 50) — each is divisible by 2, so none can be prime.
Remove multiples of 3 among the remaining odd numbers: 33 (3 × 11), 39 (3 × 13), and 45 (3 × 15).
Remove multiples of 5: 35 (5 × 7).
The candidates left to check are 31, 37, 41, 43, 47, and 49. Since √50 is about 7.07, only divisibility by 2, 3, 5, and 7 needs checking for numbers up to 50.
49 = 7 × 7, so 49 is composite and is removed.
None of 31, 37, 41, 43, or 47 is divisible by 2, 3, 5, or 7, so each of them is prime.
Cross-check: Counting from 30 to 50 gives 21 numbers; removing the 11 even numbers, the 3 remaining multiples of 3, the 1 remaining multiple of 5, and 49, leaves exactly five numbers — matching the five primes found above.
Result: the complete list of primes between 30 and 50 inclusive is 31, 37, 41, 43, 47.