Finding the Fourth Proportional to 1,021.25, 1,409.31 and 555.50

Step by Step Solution

1. Step 1: Write the proportion equation
   1,021.25 : 1,409.31 = 555.50 : x
2. Step 2: Convert to fraction form
   1,021.25/1,409.31 = 555.50/x
3. Step 3: Cross multiply
   1,021.25x = 1,409.31 × 555.50
4. Step 4: Simplify right side
   1,021.25x = 782,864.66
5. Step 5: Solve for x
   x = 782,864.66/1,021.25
6. Step 6: Final answer
   x = 766.58