Finding the Fourth Proportional to 1,116.72, 1,540.91 and 644.43

Step by Step Solution

1. Step 1: Write the proportion equation
   1,116.72 : 1,540.91 = 644.43 : x
2. Step 2: Convert to fraction form
   1,116.72/1,540.91 = 644.43/x
3. Step 3: Cross multiply
   1,116.72x = 1,540.91 × 644.43
4. Step 4: Simplify right side
   1,116.72x = 993,005.41
5. Step 5: Solve for x
   x = 993,005.41/1,116.72
6. Step 6: Final answer
   x = 889.22