The speaker will arrive in ten minutes time or in ten minutes' time .Why?

问题描述:

The speaker will arrive in ten minutes time or in ten minutes' time .Why?

是 in ten minutes' time.
为什么?
这样解释吧:
one minute 你这样说
I'll be with you in one minute's time.
所以 ten minutes 要这样说
I'll be with you in ten minutes' time.