If the weight of a sea turtle doubles in one year from birth, and grows to 40 kg in 30 years, how many years will it take for the sea turtle to grow to 5 kg from birth?
一只海龟从出生起体重一年增产一倍，30年长到40千克，那么这只海龟从出生起长到5千克需要多少年．
<result>27</result>