The study found that it is most reasonable for children over the age of 8 to arrange a day's activities and sleep time at a ratio of 5:3. How many hours should one sleep a day?
研究发现，8岁以上的儿童按5：3安排一天的活动与睡眠的时间是最合理的．一天的睡眠时间应是多少小时？
<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">24 * (3/8)</gadget>
<output>9</output>

<result>9</result>