Finding the Fourth Proportional to 1,200.78, 1,797.33 and 644.71

Step by Step Solution

1. Step 1: Write the proportion equation
   1,200.78 : 1,797.33 = 644.71 : x
2. Step 2: Convert to fraction form
   1,200.78/1,797.33 = 644.71/x
3. Step 3: Cross multiply
   1,200.78x = 1,797.33 × 644.71
4. Step 4: Simplify right side
   1,200.78x = 1,158,756.62
5. Step 5: Solve for x
   x = 1,158,756.62/1,200.78
6. Step 6: Final answer
   x = 965.01