Finding the Fourth Proportional to 1,921.83, 2,880.69 and 688.91

Step by Step Solution

1. Step 1: Write the proportion equation
   1,921.83 : 2,880.69 = 688.91 : x
2. Step 2: Convert to fraction form
   1,921.83/2,880.69 = 688.91/x
3. Step 3: Cross multiply
   1,921.83x = 2,880.69 × 688.91
4. Step 4: Simplify right side
   1,921.83x = 1,984,521.10
5. Step 5: Solve for x
   x = 1,984,521.10/1,921.83
6. Step 6: Final answer
   x = 1,032.62