Finding the Fourth Proportional to 1,141.78, 1,575.62 and 644.42

Step by Step Solution

1. Step 1: Write the proportion equation
   1,141.78 : 1,575.62 = 644.42 : x
2. Step 2: Convert to fraction form
   1,141.78/1,575.62 = 644.42/x
3. Step 3: Cross multiply
   1,141.78x = 1,575.62 × 644.42
4. Step 4: Simplify right side
   1,141.78x = 1,015,361.04
5. Step 5: Solve for x
   x = 1,015,361.04/1,141.78
6. Step 6: Final answer
   x = 889.28