Finding the Fourth Proportional to 1,108.72, 1,530.28 and 643.04

Step by Step Solution

1. Step 1: Write the proportion equation
   1,108.72 : 1,530.28 = 643.04 : x
2. Step 2: Convert to fraction form
   1,108.72/1,530.28 = 643.04/x
3. Step 3: Cross multiply
   1,108.72x = 1,530.28 × 643.04
4. Step 4: Simplify right side
   1,108.72x = 984,031.25
5. Step 5: Solve for x
   x = 984,031.25/1,108.72
6. Step 6: Final answer
   x = 887.54