Finding the Fourth Proportional to 1,085.59, 1,498.02 and 643.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.59 : 1,498.02 = 643.42 : x
2. Step 2: Convert to fraction form
   1,085.59/1,498.02 = 643.42/x
3. Step 3: Cross multiply
   1,085.59x = 1,498.02 × 643.42
4. Step 4: Simplify right side
   1,085.59x = 963,856.03
5. Step 5: Solve for x
   x = 963,856.03/1,085.59
6. Step 6: Final answer
   x = 887.86