Finding the Fourth Proportional to 1,129.32, 1,560.59 and 815.55

Step by Step Solution

1. Step 1: Write the proportion equation
   1,129.32 : 1,560.59 = 815.55 : x
2. Step 2: Convert to fraction form
   1,129.32/1,560.59 = 815.55/x
3. Step 3: Cross multiply
   1,129.32x = 1,560.59 × 815.55
4. Step 4: Simplify right side
   1,129.32x = 1,272,732.30
5. Step 5: Solve for x
   x = 1,272,732.30/1,129.32
6. Step 6: Final answer
   x = 1,126.99