Question 1131955: From a pack of 9 cards numbered 1-9, three cards are drawn at random and laid on a table from left to right. What is the probability that the number formed exceeds 400?
I know the 1st digit has to be 4,5,6,7,8 or 9, but don't know how to calculate the no. of ways.
Answer by greenestamps(13200)   (Show Source):
You can put this solution on YOUR website!
I don't know what you mean when you say you don't know how to calculate the "number of ways".
The number of ways of what?
The only thing that matters is the first digit; you don't care about the remaining digits. If the first digit is 4, 5, 6, 7, 8, or 9, then the 3-digit number will be greater than 400; if the first digit is 1, 2, or 3, it will not be.
So 6 out of the 9 possible first digits give you what you want; the probability is 6/9, or 2/3.
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