Answer:
Therefore,
Dimension of Alex playground is
20 inch × 20 inch
Explanation:
Given:
Alex is planning on making a square shape playground in the back yard.
He wants me to only use 400 square inches
Area of Square Play ground = 400 square inches
To Find:
Dimension of his playground = ?
Solution:
Let the square ground dimension be "x"
We know area of Square is given as

Substituting the values we get

Square Rooting we get

Therefore,
Dimension of Alex playground is
20 inch × 20 inch