Finding the Fourth Proportional to 1,120.59, 1,680.27 and 688.05

Step by Step Solution

1. Step 1: Write the proportion equation
   1,120.59 : 1,680.27 = 688.05 : x
2. Step 2: Convert to fraction form
   1,120.59/1,680.27 = 688.05/x
3. Step 3: Cross multiply
   1,120.59x = 1,680.27 × 688.05
4. Step 4: Simplify right side
   1,120.59x = 1,156,109.77
5. Step 5: Solve for x
   x = 1,156,109.77/1,120.59
6. Step 6: Final answer
   x = 1,031.70