Finding the Fourth Proportional to 1,085.91, 1,498.55 and 644.18

Step by Step Solution

1. Step 1: Write the proportion equation
   1,085.91 : 1,498.55 = 644.18 : x
2. Step 2: Convert to fraction form
   1,085.91/1,498.55 = 644.18/x
3. Step 3: Cross multiply
   1,085.91x = 1,498.55 × 644.18
4. Step 4: Simplify right side
   1,085.91x = 965,333.06
5. Step 5: Solve for x
   x = 965,333.06/1,085.91
6. Step 6: Final answer
   x = 888.97