There are 40 people in a class. After an exam, the rankings were ranked according to the results. As a result, the average score of the top 25 was 10 points higher than the average score of the bottom 15. A classmate was not clear about the concept of "average". He added the average score of the top 25 to the average score of the bottom 15, and then divided it by 2. He mistakenly thought that this was the average score of the whole class. How much is the average score lowered?
某班有40人．在一次考试后，按成绩排了名次，结果前25名的平均分数比后15名的平均分数多10分．一位同学对"平均"的概念不清楚，他把前25名的平均分数加上后15名的平均分数，再除以2，错误地认为这就是全班的平均分数，这样做，全班的平均分数降低了多少分．
<gadget id="calculator">60 * 15</gadget>
<output>900</output>

<gadget id="calculator">60 + 10</gadget>
<output>70</output>

<gadget id="calculator">70 * 25</gadget>
<output>1_750</output>

<gadget id="calculator">900 + 1_750</gadget>
<output>2_650</output>

<gadget id="calculator">2_650 / 40</gadget>
<output>265/4 = around 66.25</output>

<gadget id="calculator">60 + 70</gadget>
<output>130</output>

<gadget id="calculator">130 / 2</gadget>
<output>65</output>

<gadget id="calculator">(265/4) - 65</gadget>
<output>5/4 = around 1.25</output>

<result>5/4 = around 1.25</result>