1.

The digits 1,2,3,4,5,6,7,8 and 9 are written in random order to form a nine digit number. The probability that this number is divisible by 4, isA. `(1)/(9)`B. `(2)/(3)`C. `(2)/(9)`D. `(7)/(9)`

Answer» Correct Answer - C
There are `.^(9)P_(9)=9!` ways of arranging the given digits to form a nine digit number. So, total number of 9 digit numbers formed by the given digits =9!.
Out of these 9! Numbers only those numbers are divisble by 4 which have their last digits as even natural number and the numbers formed by their last two digits are divisible by 4.
The various possibilities of last two digits are :
12, 32, 52, 72, 92
24, 64, 84
16, 36, 56, 76, 96
28, 48, 68
This means that there are 16 ways of choosing the last two digits. Corresponding to each of these ways the remaining 7 digits can be arranged in 7! ways. Therefore, the total number of 9 digit numbers divisble by 4 is `16xx7!`
Hence, required probability `=(16xx7!)/(9!)=(2)/(9)`


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