Update abstract description for sphere volume calculation

Author: Gmac4247

index.html

@@ -330,7 +330,7 @@
     "mathExpression-input": "required sphere_radius=3_Volume=?",
      "mathExpression-output": "Volume = ( sqrt(3.2) * radius )^3",
     "about": "A sphere is a 3 dimensional solid shape. Its measurable property is its diameter. Its radius is half of the diameter. Its projection is a circle. Related shapes are circle, cylinder, cube and cone.",
-	"abstract": "The volume of a sphere equals the cubic value of the square root of its cross sectional area, just like a cube. The volume of a sphere is calculated as (√(3.2) × radius)³. You first take the square root of 3.2, multiply by the radius, and then cube the result. This is not (3.2 × radius)³, but (√(3.2) × radius)³. The edge length of the cube, which has the same volume as the sphere, equals the square root of the area of the square that has the same area as the sphere's cross-section.",
+	"abstract": "The volume of a sphere equals the cubic value of the square root of its cross sectional area, just like a cube. The volume of a sphere is calculated as (√(3.2) × radius)³. You first take the square root of 3.2, multiply by the radius, and then cube the result. This is not (3.2 × radius)³, but (4 × radius / √5)³.",
 	"educationalLevel": "advanced",
 	"keywords": "radius, volume",
 	"image": "sphereAndCubeMarkup.jpeg",