There is a batch of parts, the ratio of qualified to unqualified is 4:1, then what is the pass rate of this batch of parts.
有一批零件，合格的与不合格的数量之比是4：1，那么这批零件的合格率是多少．
<gadget id="calculator">4 + 1</gadget>
<output>5</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">100 / 100</gadget>
<output>1</output>

<gadget id="calculator">(4/5) * 1</gadget>
<output>4/5 = around 0.8</output>

<result>4/5 = around 0.8</result>