Question 14 of 36intermediate🔧 ApplyNumerical2 marks

Write three pairs of prime numbers less than 20 whose sum is a multiple of 5.

Correct Answer

Step 1: List prime numbers less than 20: 2, 3, 5, 7, 11, 13, 17, 19.

Step 2: Find pairs whose sum is divisible by 5.

Step 3: 2+3=5 (multiple of 5) ✓

Step 4: 2+13=15 (multiple of 5) ✓

Step 5: 3+17=20 (multiple of 5) ✓

Answer: Three pairs of prime numbers less than 20 whose sum is a multiple of 5: (2, 3) sum = 5 (2, 13) sum = 15 (3, 17) sum = 20

Exercise: Figure it Out (Section 3) | Q: 5 | (Page Page 8)
For More Understanding

Explanation

Prime numbers less than 20 are: 2, 3, 5, 7, 11, 13, 17, 19. We need pairs whose sum is divisible by 5. Checking: 2+3=5✓, 2+13=15✓, 3+7=10✓, 3+17=20✓, 7+13=20✓, 11+19=30✓. Multiple valid answers exist.

Solution Steps

  1. Step 1: List primes less than 20: 2, 3, 5, 7, 11, 13, 17, 19.

  2. Step 2: Find pairs whose sum is divisible by 5.

  3. Step 3: 2+3=5 (multiple of 5) ✓

  4. Step 4: 2+13=15 (multiple of 5) ✓

  5. Step 5: 3+17=20 (multiple of 5) ✓

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