Finding the Fourth Proportional to 1,086.16, 1,499.11 and 644.30

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.16 : 1,499.11 = 644.30 : x
2. Step 2: Convert to fraction form
   1,086.16/1,499.11 = 644.30/x
3. Step 3: Cross multiply
   1,086.16x = 1,499.11 × 644.30
4. Step 4: Simplify right side
   1,086.16x = 965,881.52
5. Step 5: Solve for x
   x = 965,881.52/1,086.16
6. Step 6: Final answer
   x = 889.26