There are 6 cards, which are written 3, 3, 4, 4, 5, 5 in sequence, what is the probability that two of them are a pair?
有6张牌，依次写着3、3、4、4、5、5，从中任取两张是一对的可能性为几分之几？
<gadget id="calculator">3 / 15</gadget>
<output>1/5 = around 0.2</output>

<result>1/5 = around 0.2</result>