Finding the Fourth Proportional to 1,375.86, 2,061.55 and 644.83

Step by Step Solution

1. Step 1: Write the proportion equation
   1,375.86 : 2,061.55 = 644.83 : x
2. Step 2: Convert to fraction form
   1,375.86/2,061.55 = 644.83/x
3. Step 3: Cross multiply
   1,375.86x = 2,061.55 × 644.83
4. Step 4: Simplify right side
   1,375.86x = 1,329,349.29
5. Step 5: Solve for x
   x = 1,329,349.29/1,375.86
6. Step 6: Final answer
   x = 966.20