Finding the Fourth Proportional to 1,086.10, 1,498.14 and 643.69

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.10 : 1,498.14 = 643.69 : x
2. Step 2: Convert to fraction form
   1,086.10/1,498.14 = 643.69/x
3. Step 3: Cross multiply
   1,086.10x = 1,498.14 × 643.69
4. Step 4: Simplify right side
   1,086.10x = 964,333.99
5. Step 5: Solve for x
   x = 964,333.99/1,086.10
6. Step 6: Final answer
   x = 887.89