Finding the Fourth Proportional to 1,218.83, 1,681.83 and 687.67

Step by Step Solution

1. Step 1: Write the proportion equation
   1,218.83 : 1,681.83 = 687.67 : x
2. Step 2: Convert to fraction form
   1,218.83/1,681.83 = 687.67/x
3. Step 3: Cross multiply
   1,218.83x = 1,681.83 × 687.67
4. Step 4: Simplify right side
   1,218.83x = 1,156,539.83
5. Step 5: Solve for x
   x = 1,156,539.83/1,218.83
6. Step 6: Final answer
   x = 948.90