Finding the Third Proportional to 421,615 and 616,647.50

Step by Step Solution

1. Step 1: Write the proportion equation
   421,615 : 616,647.50 = 616,647.50 : x
2. Step 2: Convert to fraction form
   421,615/616,647.50 = 616,647.50/x
3. Step 3: Cross multiply
   421,615x = 616,647.50 × 616,647.50
4. Step 4: Simplify right side
   421,615x = 380,254,139,256.25
5. Step 5: Solve for x
   x = 380,254,139,256.25/421,615
6. Step 6: Final answer
   x = 901,898.98