Finding the Fourth Proportional to 1,987.31, 2,981.51 and 688.61

Step by Step Solution

1. Step 1: Write the proportion equation
   1,987.31 : 2,981.51 = 688.61 : x
2. Step 2: Convert to fraction form
   1,987.31/2,981.51 = 688.61/x
3. Step 3: Cross multiply
   1,987.31x = 2,981.51 × 688.61
4. Step 4: Simplify right side
   1,987.31x = 2,053,097.60
5. Step 5: Solve for x
   x = 2,053,097.60/1,987.31
6. Step 6: Final answer
   x = 1,033.10