Survival rate refers to the percentage of surviving trees in the total number of trees.

The calculation method is: survival rate = number of surviving plants/total number of plants ×100%;

To minimize the number of trees planted, we must ensure the highest survival rate, that is, 80%;

The survival rate of 80% can be obtained by calculating the total number of plants according to the formula.

400/80% = 500 trees

A: At least 500 seedlings should be planted.

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