Finding the Fourth Proportional to 1,086.60, 1,499.40 and 644.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,086.60 : 1,499.40 = 644.42 : x
2. Step 2: Convert to fraction form
   1,086.60/1,499.40 = 644.42/x
3. Step 3: Cross multiply
   1,086.60x = 1,499.40 × 644.42
4. Step 4: Simplify right side
   1,086.60x = 966,243.35
5. Step 5: Solve for x
   x = 966,243.35/1,086.60
6. Step 6: Final answer
   x = 889.24