Finding the Fourth Proportional to 309,640.64, 427,434.72 and 209,174.72

Step by Step Solution

1. Step 1: Write the proportion equation
   309,640.64 : 427,434.72 = 209,174.72 : x
2. Step 2: Convert to fraction form
   309,640.64/427,434.72 = 209,174.72/x
3. Step 3: Cross multiply
   309,640.64x = 427,434.72 × 209,174.72
4. Step 4: Simplify right side
   309,640.64x = 89,408,537,874.28
5. Step 5: Solve for x
   x = 89,408,537,874.28/309,640.64
6. Step 6: Final answer
   x = 288,749.36