Finding the Fourth Proportional to 1,129.55, 1,558.91 and 687.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,129.55 : 1,558.91 = 687.42 : x
2. Step 2: Convert to fraction form
   1,129.55/1,558.91 = 687.42/x
3. Step 3: Cross multiply
   1,129.55x = 1,558.91 × 687.42
4. Step 4: Simplify right side
   1,129.55x = 1,071,627.63
5. Step 5: Solve for x
   x = 1,071,627.63/1,129.55
6. Step 6: Final answer
   x = 948.73