Gate2017 cs Q5

0. The probability that a k-digit number does NOT contain the digits 0,5, or 9 is-

Answer
Comment
Array

Option : C
Explanation :
Total Possibilities =(10)k,">(10)^k because every digit has 10">10 options from 0to9.">0 to 9 .
Possibility of not containing any digit 0,5,9=(7)k,">0,5,9=(7)^k, now every digit has 7">7 options.
Asked probability =(7)k(10)k=(0.7)k">(7)^k/(10)^k=(0.7)^k
So C is the answer.

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