Finding the Third Proportional to 200,128.78 and 428,859.42

Step by Step Solution

1. Step 1: Write the proportion equation
   200,128.78 : 428,859.42 = 428,859.42 : x
2. Step 2: Convert to fraction form
   200,128.78/428,859.42 = 428,859.42/x
3. Step 3: Cross multiply
   200,128.78x = 428,859.42 × 428,859.42
4. Step 4: Simplify right side
   200,128.78x = 183,920,403,730.96
5. Step 5: Solve for x
   x = 183,920,403,730.96/200,128.78
6. Step 6: Final answer
   x = 919,010.26