The survival rate of a kind of sapling after trial planting is 95%. If this kind of tree is to be planted now, how many trees should be planted in order to ensure that 380 trees will survive.
一种树苗经试种后成活率为95%，现要种这种树，为保证成活380棵，至少应种多少棵．
<gadget id="calculator">95 / 100</gadget>
<output>19/20 = around 0.95</output>

<gadget id="calculator">380 / (19/20)</gadget>
<output>400</output>

<result>400</result>