Finding the Fourth Proportional to 1,386.20, 1,912.84 and 756.72

Step by Step Solution

1. Step 1: Write the proportion equation
   1,386.20 : 1,912.84 = 756.72 : x
2. Step 2: Convert to fraction form
   1,386.20/1,912.84 = 756.72/x
3. Step 3: Cross multiply
   1,386.20x = 1,912.84 × 756.72
4. Step 4: Simplify right side
   1,386.20x = 1,447,484.28
5. Step 5: Solve for x
   x = 1,447,484.28/1,386.20
6. Step 6: Final answer
   x = 1,044.21