Finding the Fourth Proportional to 1,209.59, 1,814.43 and 429.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,209.59 : 1,814.43 = 429.71 : x
2. Step 2: Convert to fraction form
   1,209.59/1,814.43 = 429.71/x
3. Step 3: Cross multiply
   1,209.59x = 1,814.43 × 429.71
4. Step 4: Simplify right side
   1,209.59x = 779,678.72
5. Step 5: Solve for x
   x = 779,678.72/1,209.59
6. Step 6: Final answer
   x = 644.58