Finding the Third Proportional to 420,373 and 640,279.50

Step by Step Solution

1. Step 1: Write the proportion equation
   420,373 : 640,279.50 = 640,279.50 : x
2. Step 2: Convert to fraction form
   420,373/640,279.50 = 640,279.50/x
3. Step 3: Cross multiply
   420,373x = 640,279.50 × 640,279.50
4. Step 4: Simplify right side
   420,373x = 409,957,838,120.25
5. Step 5: Solve for x
   x = 409,957,838,120.25/420,373
6. Step 6: Final answer
   x = 975,224.00