How many 4-digit odd numbers can be formed using the digits {1, 2, 3, 4, 5} without repetition?
Answer and explanation
Correct answer: A. 72 numbers
- Step 1: The last digit must be odd: choices are 1, 3, 5 (3 options). Step 2. For the remaining 3 positions, choose from the 4 remaining digits: P(4, 3) = 4 3 2 = 24. Step 3. Total = 24 3 = 72 numbers. Answer: 72 numbers. Why not the others:* 120 is the total permutations of all 5 digits.
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