Finding the Fourth Proportional to 399,817.89, 551,710.71 and 218,518.29

Step by Step Solution

1. Step 1: Write the proportion equation
   399,817.89 : 551,710.71 = 218,518.29 : x
2. Step 2: Convert to fraction form
   399,817.89/551,710.71 = 218,518.29/x
3. Step 3: Cross multiply
   399,817.89x = 551,710.71 × 218,518.29
4. Step 4: Simplify right side
   399,817.89x = 120,558,880,923.89
5. Step 5: Solve for x
   x = 120,558,880,923.89/399,817.89
6. Step 6: Final answer
   x = 301,534.48