Finding the Fourth Proportional to 1,038.50, 1,556.82 and 518.21

Step by Step Solution

1. Step 1: Write the proportion equation
   1,038.50 : 1,556.82 = 518.21 : x
2. Step 2: Convert to fraction form
   1,038.50/1,556.82 = 518.21/x
3. Step 3: Cross multiply
   1,038.50x = 1,556.82 × 518.21
4. Step 4: Simplify right side
   1,038.50x = 806,751.91
5. Step 5: Solve for x
   x = 806,751.91/1,038.50
6. Step 6: Final answer
   x = 776.85