Finding the Fourth Proportional to 1,109.38, 1,530.81 and 643.46

Step by Step Solution

1. Step 1: Write the proportion equation
   1,109.38 : 1,530.81 = 643.46 : x
2. Step 2: Convert to fraction form
   1,109.38/1,530.81 = 643.46/x
3. Step 3: Cross multiply
   1,109.38x = 1,530.81 × 643.46
4. Step 4: Simplify right side
   1,109.38x = 985,015.00
5. Step 5: Solve for x
   x = 985,015.00/1,109.38
6. Step 6: Final answer
   x = 887.90