Finding the Fourth Proportional to 1,168.76, 1,612.88 and 644.80

Step by Step Solution

1. Step 1: Write the proportion equation
   1,168.76 : 1,612.88 = 644.80 : x
2. Step 2: Convert to fraction form
   1,168.76/1,612.88 = 644.80/x
3. Step 3: Cross multiply
   1,168.76x = 1,612.88 × 644.80
4. Step 4: Simplify right side
   1,168.76x = 1,039,985.02
5. Step 5: Solve for x
   x = 1,039,985.02/1,168.76
6. Step 6: Final answer
   x = 889.82