Below is an instruction that describes a task. Write a response that appropriately completes the request in Chinese. Please answer in Chinese.

### Instruction:
 一座火山爆发并向天空喷射灰烬。灰烬云在直径上扩散出喷射到天空的距离的十八倍。如果灰烬喷射到天空高度为三百英尺，灰烬云的半径是多少英尺？


### Response:
 灰烬云在直径上扩散了300 * 18 = <<300*18=5400>>5400英尺。
半径是直径的一半，所以灰烬云的半径为5400 / 2 = <<5400/2=2700>>2700英尺。