In a 5 digit ID number, what is the probability of exactly 4 digits are the digit 2? Choose the correct choice from the following choices:
A) 0.81 B) 1 C) 11/22500 D) 0.0081 E) .144
Total number of 5 digit numbers = 9 * 10 * 10 * 10 * 10 = 90,000   No. of ways of arranging 4 digits as 2 = 5C4=5.   Arrangements are as follows. Here X can be any digit other than 2   1) 2222X = no. of ways = 9   2) 2X222 = no. of ways = 9   3) 22X22 = no. of ways = 9   4) X2222 = no. of ways = 8   5) 222X2 = no. of ways = 9   Probability = (9+9+9+9+8)/90000   =11/22500   Ans - 11/22500
<result>C</result>
In a 5 digit ID number, what is the probability of exactly 4 digits are the digit 2?