Finding the Fourth Proportional to 1,141.88, 1,575.86 and 644.60

Step by Step Solution

1. Step 1: Write the proportion equation
   1,141.88 : 1,575.86 = 644.60 : x
2. Step 2: Convert to fraction form
   1,141.88/1,575.86 = 644.60/x
3. Step 3: Cross multiply
   1,141.88x = 1,575.86 × 644.60
4. Step 4: Simplify right side
   1,141.88x = 1,015,799.36
5. Step 5: Solve for x
   x = 1,015,799.36/1,141.88
6. Step 6: Final answer
   x = 889.59