A batch of products, the ratio of qualified products to unqualified products is 4:1, what is the unqualified rate of these products
一批产品，合格产品与不合格产品的比是4：1，这些产品的不合格率是多少
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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