If a 4- digit number is formed at random using the digit

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If a 4- digit number is formed at random using the digit 1, 3, 5, 7 and 9 without repetition, then the probability that it is divisible by 5, is

1. 4/5
2. 3/5
3. 1/5
4. 2/3
5. None of the above

Correct Option: C

Number of 4- digit numbers which are formed with 1, 3, 5, 7, 9 = ⁵P₄
= 5 x 4 x 3 x 2 = 120 = n (s)

Number of 4 digit number which are formed with 1, 3, 5, 7, 9 and are divisible by 5 = ⁴P₃
= 4 x 3 x 2 = 24 = n (E)

∴ p(E) = n(E)/n( s) = 24/120
= 1/5