Finding the Fourth Proportional to 1,168.75, 1,612.88 and 644.78

Step by Step Solution

1. Step 1: Write the proportion equation
   1,168.75 : 1,612.88 = 644.78 : x
2. Step 2: Convert to fraction form
   1,168.75/1,612.88 = 644.78/x
3. Step 3: Cross multiply
   1,168.75x = 1,612.88 × 644.78
4. Step 4: Simplify right side
   1,168.75x = 1,039,952.77
5. Step 5: Solve for x
   x = 1,039,952.77/1,168.75
6. Step 6: Final answer
   x = 889.80