Finding the Fourth Proportional to 1,086.07, 1,498.78 and 644.19

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.07 : 1,498.78 = 644.19 : x
2. Step 2: Convert to fraction form
   1,086.07/1,498.78 = 644.19/x
3. Step 3: Cross multiply
   1,086.07x = 1,498.78 × 644.19
4. Step 4: Simplify right side
   1,086.07x = 965,499.09
5. Step 5: Solve for x
   x = 965,499.09/1,086.07
6. Step 6: Final answer
   x = 888.98