If a bamboo pole with a length of 1.2 meters is erected on the ground, its shadow length is measured to be 1.8 meters, and the shadow length of a big tree is 7.2 meters. How tall is the tree? (answer with ratio)
如果把一根长1.2米的竹竿直立在地上，测得它的影长1.8米，一棵大树的影长7.2米，这棵大树高多少米？(用比例解答)
<gadget id="calculator">1.8 / 1.2</gadget>
<output>1.5</output>

<gadget id="calculator">7.2 / 1.5</gadget>
<output>4.8</output>

<result>4.8</result>