Answer:
20%
Explanation:
To know the percentage of apples that are not ripe yet, we just need to divide the number of apples not ripe by the number of apples in total.
As the problem says that for every 5 apples, 1 of them is not ripe, we just need to divide 1 by 5 to know the percentage of apples not ripe:
1/5 = 0.2 = 20%
So 20% of apples are not ripe yet.