Zhao Xin got 8 questions right and 2 questions wrong in the oral arithmetic practice. What is his error rate?
赵新在口算练习中做对了8道题，做错了2道，他的错误率是多少
<gadget id="calculator">8 + 2</gadget>
<output>10</output>

<gadget id="calculator">2 / 10</gadget>
<output>1/5 = around 0.2</output>

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

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

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