Asquare pyramid resting on its base is filled to half it's height with 320cubic cm of water. how much water is needed to finish filling the pyramid?

The formula for solving volume of a square pyramid is:
Volume = 1/3*h*b²

Solving for the remaining space to be filled up:
320 = 1/3*h*b² - 1/3*(h/2)(b/2)²
320=1/3hb² - 1/3h/2b²/4
320= 1/3 (7/8hb²)
Divide both sides by 7/8:
320(8/7)=1/3hb²
Volume = 45.714 cm³

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