On Sunday, Wang Yu and Zhao Qiang measured the shadow length of a 1.5-meter-long bamboo pole in the square, and the shadow length was 1 meter. At the same time, they also measured the shadow length of a big tree on the square, which was 4 meters. How tall is the tree?
星期天，王宇和赵强在广场上量的一根1.5米长的竹竿影长是1米，同时他们还量的广场上的一棵大树的影长是4米，大树有多高？
<gadget id="calculator">1.5 * 4</gadget>
<output>6</output>

<result>6</result>