Finding the Fourth Proportional to 1,005.94, 1,509.56 and 428.82

Step by Step Solution

1. Step 1: Write the proportion equation
   1,005.94 : 1,509.56 = 428.82 : x
2. Step 2: Convert to fraction form
   1,005.94/1,509.56 = 428.82/x
3. Step 3: Cross multiply
   1,005.94x = 1,509.56 × 428.82
4. Step 4: Simplify right side
   1,005.94x = 647,329.52
5. Step 5: Solve for x
   x = 647,329.52/1,005.94
6. Step 6: Final answer
   x = 643.51