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Method a.)
Since as long as 1 of the 2 cards is even, then the product of 2 cards must even

Step 1: Find the total possible outcome.
Since 2 cards are drawn from 9, so, there have 9^2;
then minus the same number of cards(which is impossible to exits at the same time), that is 9
Thus, total possible outcome is 9^2 - 9 = 72

Step 2: Count the even product.
If the fisrt is odd, the even product outcome
= 5 odd number at first (1, 3, 5, 7 and 9) * 4 even number at second (2, 4, 6 and 8)
= 5*4
=20
If the fisrt is even, the even product outcome
= 4 even number at first (2, 4, 6 and 8) * 8 number at second (any number except the number in fisrt draw)
= 4*8
= 32
Total Even outcome = 52
Hence the probabity of even product = 52/ 72 = 13/18




Method b.)
The product will be odd only if both cards are odd
First draw is odd = 5/9
Second draw is odd = 4/8
So, probability of the odd product = 20/72
Hence, probability of the odd product = 52/72 =13/18

有9張CARDS咁就有81個可能,但係without replacement,姐係無減9個可能,一共得72個可能

evenX even= even
odd X even= even
evenX odd= even
odd Xodd = odd

1至9有5個單數,so that全部有25個可能,但係without replacement,姐係無減5個可能,一共得20個可能

1－ the product of the numbers is odd
＝the product of the numbers is even
＝1－20/72
＝52/72
＝13/18