Finding the Fourth Proportional to 1,109.12, 1,530.24 and 643.04

Step by Step Solution

1. Step 1: Write the proportion equation
   1,109.12 : 1,530.24 = 643.04 : x
2. Step 2: Convert to fraction form
   1,109.12/1,530.24 = 643.04/x
3. Step 3: Cross multiply
   1,109.12x = 1,530.24 × 643.04
4. Step 4: Simplify right side
   1,109.12x = 984,005.53
5. Step 5: Solve for x
   x = 984,005.53/1,109.12
6. Step 6: Final answer
   x = 887.19