Out of 10 products, there are 6 authentic and 4 defective, what is the probability that 1 randomly selected is defective?
在10件产品有6件正品，4件次品，任意抽取1件是次品的可能性是多少．
<gadget id="calculator">4 / 10</gadget>
<output>2/5 = around 0.4</output>

<result>2/5 = around 0.4</result>