Finding the Fourth Proportional to 1,086.60, 1,499.47 and 644.19

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.60 : 1,499.47 = 644.19 : x
2. Step 2: Convert to fraction form
   1,086.60/1,499.47 = 644.19/x
3. Step 3: Cross multiply
   1,086.60x = 1,499.47 × 644.19
4. Step 4: Simplify right side
   1,086.60x = 965,943.58
5. Step 5: Solve for x
   x = 965,943.58/1,086.60
6. Step 6: Final answer
   x = 888.96