Xiao Ming's height is 1.5 meters, and his shadow length is 3 meters. If the shadow length of a tree measured at the same time and place is 4 meters, what is the actual height of the tree in meters? (Answer with proportional knowledge)
小明的身高是1.5米，他的影长是3米．在同一时间、同一地点量得一棵树的影长是4米，这棵树的实际高度是多少米？(用比例知识解答)
<gadget id="calculator">1.5 / 3</gadget>
<output>0.5</output>

<gadget id="calculator">0.5 * 4</gadget>
<output>2</output>

<result>2</result>